(1) Favorite Book - "Three Cups of Tea," chronicling the story of Greg Mortensen, an American mountaineer who, through a series of incredible events, took up the cause of building schools in Northwestern Pakistan and Afganistan, is a great way to close out the year. Mortensen's work (upwards of 70 projects in the region) in education, public health and skill building has probably done more (per dollar or per unit effort) to fight the likely root causes of terrorism - poverty and extremely high opportunity costs to obtaining education and skills - than anything else in recent memory.
A good story to remind us how to go about "going about" next year (and subsequent ones, as well).
(2) Favorite Film - A good hard look at crime, terrorism, civil liberties and how far "good" can go before crossing the line, along with some ridiculously sharp acting by Christian Bale, Heath Ledger and Aaron Eckhart, compels me to put "The Dark Knight" at the top of my film list. Just because the Academy is too stodgy to give "popcorn flicks" Best Picture nominations doesn't mean that this phenomenal movie shouldn't get a nod. (Other favorites: "The Visitor," "Wall-E," "Slumdog Millionaire," and "Milk").
(By the way, "Least Favorite Trailer of 2008" goes to the one for the forthcoming Meryl Streep film "Doubt." Not only was it bizarre the first time around, I've been exposed to it before every movie I've seen in the last six months. Do they ever plan on releasing this film, or is the strategy to just keep showing the preview over and over for some extended period of time?)
(3) Favorite Academic Discourse - Is happiness contagious? James Fowler and Nicholas Christakis argue that it is: you will be happier if you have happier friends, or if your friends have friends who have happy friends. Fowler and Christakis have also argued in the past that obesity and smoking are contagious, as well.
In the same issue of the BMJ containing the happiness piece, Ethan Cohen-Cole and Jason Fletcher (the latter of Yale University) argue that Fowler and Christakis' methodology to examine peer or social-network effects is faulty in that they do not fully control for the common environment shared by all the individuals in the network (after all, you and your friends may be happy because all of you were exposed to a city-wide balloon race or something like this). Using the Fowler-Christakis setup, they are able to show that things that shouldn't be contagious - acne, height and headaches - appear to be susceptible to peer effects just like happiness. When fully controlling for the common environment, these spurious causal effects disappear. (Yup, "Favorite Falsification Test of 2008").
Guess which piece got all the press attention. Justin Wolfers at Freakonomics has a good commentary on the discourse and the manner in which it was reported.
(4) Favorite Post - I really had a good time writing this one.
(5) Favorite Historic Moment - That Obama guy winning.
And, finally, best wishes for the New Year! I'll see you in 2009.
Tuesday, December 30, 2008
Monday, December 29, 2008
Harvey Milk Documentary on Hulu
I just found out that you can watch the documentary, "The Times of Harvey Milk" on hulu.com. Here is a link to the film.
I recently saw "Milk," starring Sean Penn, and found it to be extremely interesting, inspiring and ridiculously well acted. After watching the film, I was told by a few people that I might have gotten more out of the Penn version by watching the aforementioned documentary first. Regardless of what you choose to do, you should definitely see the film and check out the documentary.
I recently saw "Milk," starring Sean Penn, and found it to be extremely interesting, inspiring and ridiculously well acted. After watching the film, I was told by a few people that I might have gotten more out of the Penn version by watching the aforementioned documentary first. Regardless of what you choose to do, you should definitely see the film and check out the documentary.
Cell Phone Free
Last week, I decided to treat myself to a smartphone and ordered a Blackberry Storm. While my new unit was being activated and sent over, the SIM card on my older phone was deactivated. As I haven't yet received the Blackberry, I have been cell phone-less for the last five days or so.
Not having a phone has been an interesting experience. Some thoughts:
(1) I am much more productive now with work: I need to get a draft of my third dissertation paper done by the first week of Jan (check back in over the next few days for a summary of this work), and I've made more progress in the last week or so than over the previous four weeks.
(2) My social life has taken a tremendous hit: I sent out an e-mail to some friends and family giving them my home phone number. In spite of me being an excellent conversationalist, nobody has called my alternate number. I attribute this to the fact that having a cell phone diminishes the returns to memorizing phone numbers to zero. As such, the fixed cost of learning a new number or entering into your address book becomes high enough for people to wait until your old number comes back online to call. At least, this is what I am telling myself.
(3) My risk of getting cancer has probably remained constant: There is a growing and very controversial body of work on whether cell phone use (or exposure to mobile towers) increases ones risk of getting various tumors. Most of these studies suffer from omitted variables bias and the fact that cell phone use being widespread only for 10-15 years or so, the follow up period is just not long enough to make many of the purported positive results to actually be plausible.
(4) My risk of getting in a car accident may not have changed, either: This one is based on a really clever piece of research by Saurabh Bhargava and Vikram Pathania trying to get at the causal effects of cell phone use of traffic accidents. From their abstract:
Previous research in the laboratory and by epidemiologists has compared the danger of cell phone use while driving to that of illicit levels of alcohol. This paper investigates the causal link between driver cell phone use and crash rates by exploiting a natural experiment - the discontinuity in marginal pricing at 9pm on weekdays when cellular plans transition from peak to off-peak pricing. We first document that this pricing threshold induces a 20 to 30% jump in call volume for two samples of callers. We then document the corresponding change in the fatal and all crash rate. Using the years prior to the introduction of two-tier pricing as a control, as well as weekends as a second control, we find no evidence for a relative rise in crashes after 9pm on weekdays from 2002-2005. The upper bounds of our estimates rule out increases in all crashes larger than 1.0% and increases in fatal crashes larger than 1.3% - these upper bounds reject the increases implied by most existing studies. An analysis of regional trends in cell phone ownership and crashes, legislation banning driver cell phone use, and differences in urban and rural ownership confirm our basic result. We discuss possible explanations and present a behavioral model to reconcile this counterintuitive finding with existing research.
Not having a phone has been an interesting experience. Some thoughts:
(1) I am much more productive now with work: I need to get a draft of my third dissertation paper done by the first week of Jan (check back in over the next few days for a summary of this work), and I've made more progress in the last week or so than over the previous four weeks.
(2) My social life has taken a tremendous hit: I sent out an e-mail to some friends and family giving them my home phone number. In spite of me being an excellent conversationalist, nobody has called my alternate number. I attribute this to the fact that having a cell phone diminishes the returns to memorizing phone numbers to zero. As such, the fixed cost of learning a new number or entering into your address book becomes high enough for people to wait until your old number comes back online to call. At least, this is what I am telling myself.
(3) My risk of getting cancer has probably remained constant: There is a growing and very controversial body of work on whether cell phone use (or exposure to mobile towers) increases ones risk of getting various tumors. Most of these studies suffer from omitted variables bias and the fact that cell phone use being widespread only for 10-15 years or so, the follow up period is just not long enough to make many of the purported positive results to actually be plausible.
(4) My risk of getting in a car accident may not have changed, either: This one is based on a really clever piece of research by Saurabh Bhargava and Vikram Pathania trying to get at the causal effects of cell phone use of traffic accidents. From their abstract:
Previous research in the laboratory and by epidemiologists has compared the danger of cell phone use while driving to that of illicit levels of alcohol. This paper investigates the causal link between driver cell phone use and crash rates by exploiting a natural experiment - the discontinuity in marginal pricing at 9pm on weekdays when cellular plans transition from peak to off-peak pricing. We first document that this pricing threshold induces a 20 to 30% jump in call volume for two samples of callers. We then document the corresponding change in the fatal and all crash rate. Using the years prior to the introduction of two-tier pricing as a control, as well as weekends as a second control, we find no evidence for a relative rise in crashes after 9pm on weekdays from 2002-2005. The upper bounds of our estimates rule out increases in all crashes larger than 1.0% and increases in fatal crashes larger than 1.3% - these upper bounds reject the increases implied by most existing studies. An analysis of regional trends in cell phone ownership and crashes, legislation banning driver cell phone use, and differences in urban and rural ownership confirm our basic result. We discuss possible explanations and present a behavioral model to reconcile this counterintuitive finding with existing research.
Thursday, December 18, 2008
Nudges and Matrimonial Websites
The Freakonomics blog has a great post on the behavioral economics behind minimum-payment requirements for credit cards. Citing some recent research by Neil Stewart, the post explains how providing a minimum threshold may induce people to actually make a smaller payment than they otherwise would have. This behavior comes about because of our susceptibility to anchoring: we tend to base our decisions on even arbitrary values we are given as starting points (see here for some examples).
This result is clearly of interest to behavioral economists: decades of research at the intersection of psychology and economics has led some observers to suggest that these tools be used in policy. That is, the irrational behavioral foibles of humans can be used to "nudge" them into making the right decisions (the term comes from a new book by Richard Thaler and Cass Sunstein).
Are there other avenues where nudges may be effective? And are there (other) examples where well-intentioned nudges may be counterproductive? A good illustration for both queries comes from Indian matrimonial websites. Like all social networking, a given user's experience on a martrimonial website depends on the activities of his or her peers. Inactive individuals do not contribute anything to the marketplace, while active ones generate all sorts of positive externalities. As such, it is in the best interest of the website company to get people active, either by introducing clarity to the user interface, making the website more fun, recruiting tons of singles, or by nudging existing users to make more contacts.
Regarding the latter, one particular website keeps track of whether a given user responds to an expression of interest from another user and the number of times that user accesses the website. Based on their activity patterns, slow or shy users are then sent an e-mail urging them to use the website by saying they are (1) missing out and (2) being rude to others by not responding. While perhaps not based in behavioral economics per se, the idea is to use some form of shame and opportunity cost argument to get people more involved.
But does this nudge work? I could easily see something like this being counterproductive. After all, nobody likes a nag, and I would bet there are plenty of people who would stop using the website just to avoid being made to feel guilty. Furthermore, messages (1) and (2) are conflicting: one is positive and the other negative. This might just confuse people.
I think this sort of thing is ripe for an experiment. However, this would require some alternate nudge option. Any ideas?
This result is clearly of interest to behavioral economists: decades of research at the intersection of psychology and economics has led some observers to suggest that these tools be used in policy. That is, the irrational behavioral foibles of humans can be used to "nudge" them into making the right decisions (the term comes from a new book by Richard Thaler and Cass Sunstein).
Are there other avenues where nudges may be effective? And are there (other) examples where well-intentioned nudges may be counterproductive? A good illustration for both queries comes from Indian matrimonial websites. Like all social networking, a given user's experience on a martrimonial website depends on the activities of his or her peers. Inactive individuals do not contribute anything to the marketplace, while active ones generate all sorts of positive externalities. As such, it is in the best interest of the website company to get people active, either by introducing clarity to the user interface, making the website more fun, recruiting tons of singles, or by nudging existing users to make more contacts.
Regarding the latter, one particular website keeps track of whether a given user responds to an expression of interest from another user and the number of times that user accesses the website. Based on their activity patterns, slow or shy users are then sent an e-mail urging them to use the website by saying they are (1) missing out and (2) being rude to others by not responding. While perhaps not based in behavioral economics per se, the idea is to use some form of shame and opportunity cost argument to get people more involved.
But does this nudge work? I could easily see something like this being counterproductive. After all, nobody likes a nag, and I would bet there are plenty of people who would stop using the website just to avoid being made to feel guilty. Furthermore, messages (1) and (2) are conflicting: one is positive and the other negative. This might just confuse people.
I think this sort of thing is ripe for an experiment. However, this would require some alternate nudge option. Any ideas?
Tuesday, December 16, 2008
Yale and the Financial Crisis
Check out the detailed consequences of Yale's 25% drop in the endowment value over the last six months or so here. The situation at other American universities also looks somewhat glum.
Be Careful With Natural Experiments
Those of you who visit this space regularly know a thing or two about my obsession with causal effects. Answering many questions in health economics requires a strategy to understand the causal effect of one variable on another, and recovering such effects demands clever strategies or tools that go beyond simple multivariate models of some X on some Y. The cleanest way to get the causal effect of X on Y is to randomize X. This strategy has been used widely in laboratory and clinical medicine, and is now being exploited in a growing number of influential papers in economics and political science.
In many cases, however, it may not possible to randomize X or the question of interest involves some program or event that occurred in the past. In these situations, researchers looks for other sources of variation in X that are effectively random - the natural experiment. A good (and now famous) example from health economics involves the impact of early life events on health and socioeconomic position later in life. A great deal of early work in epidemiology found links between the disease environment faced by an individual at birth and this individuals health later in life. This link could be causal: fetal health influences organogenesis and development that goes on to influence adult health. At the same time, alternate explanations are possible: children born to poor parents become poor themselves, which affects their health. To complete the story, poor parents may tend to reside in poor, diseased areas.
To get around this issue, Douglas Almond, in an influential 2006 paper, utilized the influenza pandemic of 1918, which struck without warning, over a short period of time, and had large, notable effects. Being exposed to influenza in utero can be thought of as a random shock (a natural experiment), and Almond took advantage of this property to derive the causal effects of health in utero on outcomes later in life.
However, while the "influenza strategy" is as close to a slam dunk as you could possibly get in observational research, other things that may seem like natural experiments a priori may not be as definitively good. In fact, such variation may even lead researchers astray.
A new NBER working paper explores this issue in detail. Kasey Buckles and Daniel Hungerman consider the case of season of birth, which has been shown to be associated with a variety of health and socioeconomic outcomes later in life. These associations have been attributed to fetal exposure to different weather conditions or differential exposure to arbitrary age-cutoffs (in sports or in schooling). At first glance, season of birth appears to be a great source of exogenous variation for a slew of different causal questions: after all, individuals don't have any control over when they are born and it seems like something that would be left to chance. However, Buckles and Hungerman convincingly argue that this is not the case:
In this paper we consider a new explanation: that children born at different times in the year are conceived by women with different socioeconomic characteristics. We document large seasonal changes in the characteristics of women giving birth throughout the year in the United States. Children born in the winter are disproportionally born to women who are more likely to be teenagers and less likely to be married or have a high school degree. We show that controls for family background characteristics can explain up to half of the relationship between season of birth and adult outcomes. We then discuss the implications of this result for using season of birth as an instrumental variable; our findings suggest that, though popular, season-of-birth instruments may produce inconsistent estimates. Finally, we find that some of the seasonality in maternal characteristics is due to summer weather differentially affecting fertility patterns across socioeconomic groups.
This is a neat paper and serves as a good warning to those interested in finding natural variation to identify causal effects. Another excellent paper on the same subject, by Mark Rosenzweig and Ken Wolpin, goes through a variety of other potentially fallacious natural experiment examples and is a must read for anyone doing empirical work.
In many cases, however, it may not possible to randomize X or the question of interest involves some program or event that occurred in the past. In these situations, researchers looks for other sources of variation in X that are effectively random - the natural experiment. A good (and now famous) example from health economics involves the impact of early life events on health and socioeconomic position later in life. A great deal of early work in epidemiology found links between the disease environment faced by an individual at birth and this individuals health later in life. This link could be causal: fetal health influences organogenesis and development that goes on to influence adult health. At the same time, alternate explanations are possible: children born to poor parents become poor themselves, which affects their health. To complete the story, poor parents may tend to reside in poor, diseased areas.
To get around this issue, Douglas Almond, in an influential 2006 paper, utilized the influenza pandemic of 1918, which struck without warning, over a short period of time, and had large, notable effects. Being exposed to influenza in utero can be thought of as a random shock (a natural experiment), and Almond took advantage of this property to derive the causal effects of health in utero on outcomes later in life.
However, while the "influenza strategy" is as close to a slam dunk as you could possibly get in observational research, other things that may seem like natural experiments a priori may not be as definitively good. In fact, such variation may even lead researchers astray.
A new NBER working paper explores this issue in detail. Kasey Buckles and Daniel Hungerman consider the case of season of birth, which has been shown to be associated with a variety of health and socioeconomic outcomes later in life. These associations have been attributed to fetal exposure to different weather conditions or differential exposure to arbitrary age-cutoffs (in sports or in schooling). At first glance, season of birth appears to be a great source of exogenous variation for a slew of different causal questions: after all, individuals don't have any control over when they are born and it seems like something that would be left to chance. However, Buckles and Hungerman convincingly argue that this is not the case:
In this paper we consider a new explanation: that children born at different times in the year are conceived by women with different socioeconomic characteristics. We document large seasonal changes in the characteristics of women giving birth throughout the year in the United States. Children born in the winter are disproportionally born to women who are more likely to be teenagers and less likely to be married or have a high school degree. We show that controls for family background characteristics can explain up to half of the relationship between season of birth and adult outcomes. We then discuss the implications of this result for using season of birth as an instrumental variable; our findings suggest that, though popular, season-of-birth instruments may produce inconsistent estimates. Finally, we find that some of the seasonality in maternal characteristics is due to summer weather differentially affecting fertility patterns across socioeconomic groups.
This is a neat paper and serves as a good warning to those interested in finding natural variation to identify causal effects. Another excellent paper on the same subject, by Mark Rosenzweig and Ken Wolpin, goes through a variety of other potentially fallacious natural experiment examples and is a must read for anyone doing empirical work.
Thursday, December 11, 2008
Bad News on the Other Side of the Birth Weight Distribution?
Two recent articles explore the long-run effects of maternal weight gain and/or high weight at birth on long-run outcomes. Much of the health economics literature has focused on understanding returns to birth weight at the lower tail of the distribution, and several studies have found notable effects of birth weight on wages, schooling and cognition later in life. The downsides to high birth weight have been explored in the medical literature, which has typically focused on obesity and diabetes risk among children born to diabetic mothers (who birth larger than average - or macrosomic - infants).
A recent study in Obstetrics and Gynecology illustrates that increased gestational weight gain among mothers is associated with higher risk of obesity among their offspring. Unlike past studies, the study sample here is not limited to mothers with diabetes. While causality is difficult to establish here - mothers that gain weight during pregnancy may have similar preferences/constraints regarding food, which can be passed on to the next generation via other means besides biology - the results are interesting and deserve further research attention.
In a recent NBER working paper, Resul Cesar and Inas Rashad look at the association between birth weight and cognitive outcomes among a sample of children and teens and young adults followed in two different panel studies. The main result is that birth weight is associated with lower cognitive test scores at both the low and high part of the distribution: heavy infants suffer deficits, too.
I'm guessing this literature will likely explode in the next few years, especially with the ever growing obesity "epidemic" and its obvious consequences for maternal weight during pregnancy (see here for an earlier piece on this). Hopefully, this literature will address two major areas:
(1) Causal effects - Spatial variation in food prices, dynamics from recessions, the introduction of public programs and other shocks can be used to identify maternal weight gain during gestation and child birth weight. Utilizing this variation can help eliminate from the picture alternative interpretations of the association between maternal weight gain, child birth weight and later child outcomes.
(2) Mechanisms - Even if you can recover causal effects, what is the pathway? A link between high birth weight and lower cognition could be biological in nature or may operate through reduced and less effective investments in childhood and adolescents due to diminishing social returns to body weight: kids may learn less effectively if they are being made fun of at school for their appearance. These explanations have vastly different policy implications and should be teased apart.
A recent study in Obstetrics and Gynecology illustrates that increased gestational weight gain among mothers is associated with higher risk of obesity among their offspring. Unlike past studies, the study sample here is not limited to mothers with diabetes. While causality is difficult to establish here - mothers that gain weight during pregnancy may have similar preferences/constraints regarding food, which can be passed on to the next generation via other means besides biology - the results are interesting and deserve further research attention.
In a recent NBER working paper, Resul Cesar and Inas Rashad look at the association between birth weight and cognitive outcomes among a sample of children and teens and young adults followed in two different panel studies. The main result is that birth weight is associated with lower cognitive test scores at both the low and high part of the distribution: heavy infants suffer deficits, too.
I'm guessing this literature will likely explode in the next few years, especially with the ever growing obesity "epidemic" and its obvious consequences for maternal weight during pregnancy (see here for an earlier piece on this). Hopefully, this literature will address two major areas:
(1) Causal effects - Spatial variation in food prices, dynamics from recessions, the introduction of public programs and other shocks can be used to identify maternal weight gain during gestation and child birth weight. Utilizing this variation can help eliminate from the picture alternative interpretations of the association between maternal weight gain, child birth weight and later child outcomes.
(2) Mechanisms - Even if you can recover causal effects, what is the pathway? A link between high birth weight and lower cognition could be biological in nature or may operate through reduced and less effective investments in childhood and adolescents due to diminishing social returns to body weight: kids may learn less effectively if they are being made fun of at school for their appearance. These explanations have vastly different policy implications and should be teased apart.
Tuesday, December 9, 2008
Returns to Medical Care Among High Risk Infants
A really interesting NBER paper this week looks at health returns to medical interventions among high-risk (here, low birth weight) newborns babies. The difficulty in assessing the casual effects of medical care in this population is that worse-off infants may get more of it because they require it. On the other hand, unhealthy babies may be more likely to come from poor families, who lack access to health care. Either process makes it difficult to recover causal effects.
Douglas Almond, Joseph Doyle, Amanda E. Kowalski and Heidi Williams adopt an interesting strategy to get around this issue. Essentially, they utilize existing birth weight thresholds (those below 1500 grams are classified very low birth weight) and provider obedience to these discontinuous (and perhaps arbitrary?) thresholds. By comparing those babies just below 1500 grams to those just above it, the authors contend that they get around the targetting of medical care to worse off babies - after all, the difference of a few grams around the cutoff is likely random and unrelated to innate biological hardiness. In a sense, the level of treatment given is essentially random for babies born around this narrow threshold. More on their methodology (which Almond and Doyle employ in another very interesting paper) and results:
We estimate marginal returns to medical care for at-risk newborns by comparing health outcomes and medical treatment provision on either side of common risk classifications, most notably the "very low birth weight" threshold at 1500 grams. First, using data on the census of US births in available years from 1983-2002, we find evidence that newborns with birth weights just below 1500 grams have lower one-year mortality rates than do newborns with birth weights just above this cutoff, even though mortality risk tends to decrease with birth weight. One-year mortality falls by approximately one percentage point as birth weight crosses 1500 grams from above, which is large relative to mean one-year mortality of 5.5% just above 1500 grams. Second, using hospital discharge records for births in five states in available years from 1991-2006, we find evidence that newborns with birth weights just below 1500 grams have discontinuously higher costs and frequencies of specific medical inputs. We estimate a $4,000 increase in hospital costs as birth weight approaches 1500 grams from above, relative to mean hospital costs of $40,000 just above 1500 grams. Taken together, these estimates suggest that the cost of saving a statistical life of a newborn with birth weight near 1500 grams is on the order of $550,000 in 2006 dollars.
Aside from the policy relevance of the results and the innovative research design used in the study, I find it really interesting that the provision of health care is so sensitive to seemingly arbitrary guidelines. Does anyone have a sense of where the 1500 and 2500 gram cutoffs came from, and whether they've outlived their clinical relevance?
Douglas Almond, Joseph Doyle, Amanda E. Kowalski and Heidi Williams adopt an interesting strategy to get around this issue. Essentially, they utilize existing birth weight thresholds (those below 1500 grams are classified very low birth weight) and provider obedience to these discontinuous (and perhaps arbitrary?) thresholds. By comparing those babies just below 1500 grams to those just above it, the authors contend that they get around the targetting of medical care to worse off babies - after all, the difference of a few grams around the cutoff is likely random and unrelated to innate biological hardiness. In a sense, the level of treatment given is essentially random for babies born around this narrow threshold. More on their methodology (which Almond and Doyle employ in another very interesting paper) and results:
We estimate marginal returns to medical care for at-risk newborns by comparing health outcomes and medical treatment provision on either side of common risk classifications, most notably the "very low birth weight" threshold at 1500 grams. First, using data on the census of US births in available years from 1983-2002, we find evidence that newborns with birth weights just below 1500 grams have lower one-year mortality rates than do newborns with birth weights just above this cutoff, even though mortality risk tends to decrease with birth weight. One-year mortality falls by approximately one percentage point as birth weight crosses 1500 grams from above, which is large relative to mean one-year mortality of 5.5% just above 1500 grams. Second, using hospital discharge records for births in five states in available years from 1991-2006, we find evidence that newborns with birth weights just below 1500 grams have discontinuously higher costs and frequencies of specific medical inputs. We estimate a $4,000 increase in hospital costs as birth weight approaches 1500 grams from above, relative to mean hospital costs of $40,000 just above 1500 grams. Taken together, these estimates suggest that the cost of saving a statistical life of a newborn with birth weight near 1500 grams is on the order of $550,000 in 2006 dollars.
Aside from the policy relevance of the results and the innovative research design used in the study, I find it really interesting that the provision of health care is so sensitive to seemingly arbitrary guidelines. Does anyone have a sense of where the 1500 and 2500 gram cutoffs came from, and whether they've outlived their clinical relevance?
Friday, November 14, 2008
Hiatus
Hi everyone,
I will be taking a break from blogging for at least a month. I'm really grateful to those of you who visit this space regularly: I've learned a great deal from your comments.
I hope to resume blogging by the end of the year. If for some reason you miss my writing, you can check out my working academic papers here.
Thanks for reading, and see you soon.
Atheen
I will be taking a break from blogging for at least a month. I'm really grateful to those of you who visit this space regularly: I've learned a great deal from your comments.
I hope to resume blogging by the end of the year. If for some reason you miss my writing, you can check out my working academic papers here.
Thanks for reading, and see you soon.
Atheen
Tuesday, November 11, 2008
Random Tuesdays
Some things of note:
1) Blogger and frequent commenter in this space James Hudspeth sent me this interesting article about how google searches can be used to track disease outbreaks, with information relays that are potentially faster than existing surveillance systems.
2) Elizabeth Pisani, author of The Wisdom of Whores (on my reading list for next month), has a fun and informative blog of the same name. Here is an interesting post from this blog looking at incentives and HIV/AIDS, with a special reference to disability grants in South Africa. Here is our paper on this subject.
3) Spotlight (with a thoughtful piece) on Obama.
4) People are addictive.
5) Be sure to check out the Yale University Insitute for Social and Policy Studies 40th Year Celebration and Conference. I think space is tight, but you can still get a sense of the bill through the papers and slides available via the link provided above. The conference focuses on using experiments to answer important questions in political science and economics, and the papers span a wide range of topics. All of them are super interesting.
1) Blogger and frequent commenter in this space James Hudspeth sent me this interesting article about how google searches can be used to track disease outbreaks, with information relays that are potentially faster than existing surveillance systems.
2) Elizabeth Pisani, author of The Wisdom of Whores (on my reading list for next month), has a fun and informative blog of the same name. Here is an interesting post from this blog looking at incentives and HIV/AIDS, with a special reference to disability grants in South Africa. Here is our paper on this subject.
3) Spotlight (with a thoughtful piece) on Obama.
4) People are addictive.
5) Be sure to check out the Yale University Insitute for Social and Policy Studies 40th Year Celebration and Conference. I think space is tight, but you can still get a sense of the bill through the papers and slides available via the link provided above. The conference focuses on using experiments to answer important questions in political science and economics, and the papers span a wide range of topics. All of them are super interesting.
Friday, November 7, 2008
Obama
Addressing my graduating class, the Dean of the Duke University Chapel gave a stirring speech about how we needed to resist being labeled the 9/11 generation. Though the horrific terrorist attacks happened during our senior year, the Dean urged us to think beyond 9/11 and become the generation that made its mark by decisively and proactively moving society away from that event and towards a better future. Rather than becoming pessimistic and jaded about our world, he wanted us to use our energies, skills and talents to refocus the collective gaze of society on the good and the promising.
Nearly seven years later, I witnessed a slew of my friends taking up the Dean's challenge, inspired the first black man gaining a major party nomination for President, who embodied progress, optimism and youth, speaking of hope and change. Several friends participated directly in the Obama campaign, working long hours in battleground states, making calls and coordinating rallies. Others chose to engage in vociferous discussion with their families and friends about their beliefs and about what they felt was the most important decision our country has had to make in a long time. Still others spent election day calling complete strangers encouraging them to get out to vote. Tuesday night, and for the rest of the week thereafter, these friends and many others across the country walked around with gleaming smiles, radiating a sense of optimism that seems to be a perfectly natural extension of the events of the last few months, but also completely remarkable given the aftermath of 9/11 and the recent financial crisis. As one of my professors gushed on the day after the election: "It is now morning in America."
I think the implicit Reagan comparison is entirely appropriate. If Reagan was the transformational figure of our parents' generation, Obama is most definitely ours. Before Tuesday, though, my views on President-Elect Obama had been more muted. To me, "Hope" and "Change" were empty campaign promises that I'd heard before, made by another inspirational candidate who turned out to be an underwhelming President. If anything, I chose to vote for Obama mainly because I liked his technocratic and pragmatic outlook (and also because the erstwhile Maverick Senator McCain had become much less of one).
Tuesday taught me that these concepts are not, and had never been, just vague and hazy campaign rhetoric. Indeed, the tangible effects of being inspired by a man who has become both a symbol and a (potential) instrument for optimism and progress are substantive and significant and should not be underestimated: millions of people appear ready to make sacrifices and continue to work at a grassroots level for change. Some of the optimism appears a bit unhealthy - after all, Obama does not hold a magic wand - but I think much it can be harnessed and put to use in a way never before seen, certainly not in my lifetime.
Prior to Nov 4, 2008, 9/11 was indeed the defining historical moment of our generation. It clearly changed our views about the world and about our own country. Much of this decade has been colored by this event, from the tangible policies and actions we have taken as well as to our national mood more generally. We now have another defining moment for our generation: the election of Barack Obama to the Presidency, with all its optimism and its possibilities. Now let's put this all our good-will, excitement and sense of purpose to good use and get down in the trenches with our new President.
It's time to get to work.
Nearly seven years later, I witnessed a slew of my friends taking up the Dean's challenge, inspired the first black man gaining a major party nomination for President, who embodied progress, optimism and youth, speaking of hope and change. Several friends participated directly in the Obama campaign, working long hours in battleground states, making calls and coordinating rallies. Others chose to engage in vociferous discussion with their families and friends about their beliefs and about what they felt was the most important decision our country has had to make in a long time. Still others spent election day calling complete strangers encouraging them to get out to vote. Tuesday night, and for the rest of the week thereafter, these friends and many others across the country walked around with gleaming smiles, radiating a sense of optimism that seems to be a perfectly natural extension of the events of the last few months, but also completely remarkable given the aftermath of 9/11 and the recent financial crisis. As one of my professors gushed on the day after the election: "It is now morning in America."
I think the implicit Reagan comparison is entirely appropriate. If Reagan was the transformational figure of our parents' generation, Obama is most definitely ours. Before Tuesday, though, my views on President-Elect Obama had been more muted. To me, "Hope" and "Change" were empty campaign promises that I'd heard before, made by another inspirational candidate who turned out to be an underwhelming President. If anything, I chose to vote for Obama mainly because I liked his technocratic and pragmatic outlook (and also because the erstwhile Maverick Senator McCain had become much less of one).
Tuesday taught me that these concepts are not, and had never been, just vague and hazy campaign rhetoric. Indeed, the tangible effects of being inspired by a man who has become both a symbol and a (potential) instrument for optimism and progress are substantive and significant and should not be underestimated: millions of people appear ready to make sacrifices and continue to work at a grassroots level for change. Some of the optimism appears a bit unhealthy - after all, Obama does not hold a magic wand - but I think much it can be harnessed and put to use in a way never before seen, certainly not in my lifetime.
Prior to Nov 4, 2008, 9/11 was indeed the defining historical moment of our generation. It clearly changed our views about the world and about our own country. Much of this decade has been colored by this event, from the tangible policies and actions we have taken as well as to our national mood more generally. We now have another defining moment for our generation: the election of Barack Obama to the Presidency, with all its optimism and its possibilities. Now let's put this all our good-will, excitement and sense of purpose to good use and get down in the trenches with our new President.
It's time to get to work.
Monday, November 3, 2008
Early Life and Obesity in Mexico: Talk Weds
This Wednesday I'll be giving a talk on my research on the early life influences on obesity and hypertension among adults in Mexico. I will also speak on the links between early life conditions and health and cognitive development among adolescents in Mexico, again with a special emphasis on obesity. My presentation will follow a talk by my colleague Ulrike Muench, who will be presenting her very interesting research on gender gaps in wages paid to nurses (I believe male nurses get paid more) and the extent to which various theories may explain these differentials.
As of now, I think my talk will be pretty low-key. I plan on going through the basics of the biology linking birth and early childhood events to later health and discuss and then talk why this knowledge could be useful in enriching our understanding when and how economic factors (technological change leading to decreases in activity levels and food price declines leading to increases in income) work to lead to increases in body weight and any associated disorders. I will also present some preliminary econometric models attempting to (1) recover causal impacts of early life factors on these outcomes and (2) illustrate how the manner in which body weight (as well as blood pressure and glucose tolerance) respond to the aforementioned economic factors depends highly on environmental conditions faced at the beginning of life. Most importantly, I will unveil my research agenda for the next several months on these and related topics.
The seminar will be this Weds, Nov 5th from 1:30 - 3 PM in Rm 105 at 60 College Street (LEPH). Ulrike will open and I'll follow on as the second act. Feel free to join us if you are interested!
As of now, I think my talk will be pretty low-key. I plan on going through the basics of the biology linking birth and early childhood events to later health and discuss and then talk why this knowledge could be useful in enriching our understanding when and how economic factors (technological change leading to decreases in activity levels and food price declines leading to increases in income) work to lead to increases in body weight and any associated disorders. I will also present some preliminary econometric models attempting to (1) recover causal impacts of early life factors on these outcomes and (2) illustrate how the manner in which body weight (as well as blood pressure and glucose tolerance) respond to the aforementioned economic factors depends highly on environmental conditions faced at the beginning of life. Most importantly, I will unveil my research agenda for the next several months on these and related topics.
The seminar will be this Weds, Nov 5th from 1:30 - 3 PM in Rm 105 at 60 College Street (LEPH). Ulrike will open and I'll follow on as the second act. Feel free to join us if you are interested!
Sunday, November 2, 2008
Daylight Savings Time and Energy Consumption
I'm not a big fan of Daylight Saving Time (DST) for several reasons. Mainly, I hate the fact that the sun goes down an hour earlier during an already short-winter day. I always figure that this undermined the justification of DST as an energy saving device. After all, I need to turn on my lights in the evening an hour earlier, and this is not counterbalanced by energy savings in the morning (I don't think I wake up early enough!).
A new working paper by Matthew Kotchen and Laura Grant attempts to generate some estimates surrounding DST and energy savings. Here is the abstract of their paper:
The history of Daylight Saving Time (DST) has been long and controversial. Throughout its implementation during World Wars I and II, the oil embargo of the 1970s, consistent practice today, and recent extensions, the primary rationale for DST has always been to promote energy conservation. Nevertheless, there is surprisingly little evidence that DST actually saves energy. This paper takes advantage of a natural experiment in the state of Indiana to provide the first empirical estimates of DST effects on electricity consumption in the United States since the mid-1970s. Focusing on residential electricity demand, we conduct the first-ever study that uses micro-data on households to estimate an overall DST effect. The dataset consists of more than 7 million observations on monthly billing data for the vast majority of households in southern Indiana for three years. Our main finding is that -- contrary to the policy's intent -- DST increases residential electricity demand. Estimates of the overall increase are approximately 1 percent, but we find that the effect is not constant throughout the DST period. DST causes the greatest increase in electricity consumption in the fall, when estimates range between 2 and 4 percent. These findings are consistent with simulation results that point to a tradeoff between reducing demand for lighting and increasing demand for heating and cooling. We estimate a cost of increased electricity bills to Indiana households of $9 million per year. We also estimate social costs of increased pollution emissions that range from $1.7 to $5.5 million per year. Finally, we argue that the effect is likely to be even stronger in other regions of the United States.
Interesting stuff. Another justification I heard was that DST helps ensure the safety of schoolchildren catching the bus in the morning. It would be interesting to get some estimates on welfare gains on this margin, as well.
A new working paper by Matthew Kotchen and Laura Grant attempts to generate some estimates surrounding DST and energy savings. Here is the abstract of their paper:
The history of Daylight Saving Time (DST) has been long and controversial. Throughout its implementation during World Wars I and II, the oil embargo of the 1970s, consistent practice today, and recent extensions, the primary rationale for DST has always been to promote energy conservation. Nevertheless, there is surprisingly little evidence that DST actually saves energy. This paper takes advantage of a natural experiment in the state of Indiana to provide the first empirical estimates of DST effects on electricity consumption in the United States since the mid-1970s. Focusing on residential electricity demand, we conduct the first-ever study that uses micro-data on households to estimate an overall DST effect. The dataset consists of more than 7 million observations on monthly billing data for the vast majority of households in southern Indiana for three years. Our main finding is that -- contrary to the policy's intent -- DST increases residential electricity demand. Estimates of the overall increase are approximately 1 percent, but we find that the effect is not constant throughout the DST period. DST causes the greatest increase in electricity consumption in the fall, when estimates range between 2 and 4 percent. These findings are consistent with simulation results that point to a tradeoff between reducing demand for lighting and increasing demand for heating and cooling. We estimate a cost of increased electricity bills to Indiana households of $9 million per year. We also estimate social costs of increased pollution emissions that range from $1.7 to $5.5 million per year. Finally, we argue that the effect is likely to be even stronger in other regions of the United States.
Interesting stuff. Another justification I heard was that DST helps ensure the safety of schoolchildren catching the bus in the morning. It would be interesting to get some estimates on welfare gains on this margin, as well.
Wednesday, October 29, 2008
Expectations and Depression (and Other Interesting Links)
1. My thesis committee chair Jody Sindelar, along with Bill Gallo and Tracy Falba on the relationship between deviations from one's a priori expectations about working and subsequent depression among those around retirement age. While causality is always difficult to establish, the symmetric correlation between working longer OR shorter than expected and depressive symptoms is striking and consistent with "feelings of loss of control" type explanations for depression:
"We found significant effects on depression at age 62 both for full-time workers who expected not to be working full-time, and for participants not working full-time who expected to be doing so. These results hold even after adjustment for earlier depressive symptoms, sociodemographic and other relevant controls. The findings suggest that working longer and retiring earlier than expected each may compromise psychological well-being. The current financial crisis may result in both scenarios as some workers may have to work longer than expected due to the decline in pension and other wealth while others may retire earlier due to job loss."
2. A fantastic back-and-forth between filmmaker Oliver Stone and venerable journalists Bob Woodward, Ron Suskund and Jacob Weisberg on Stone's new tragi-comic-biopic W and the Bush (II) presidency more generally. By the way, if you haven't seen W. yet, you should.
3. Dan Ariely presents evidence that conservatives may have a better sense of humor than liberals. Surprising? Not to me.
4. Chris Blattman on pictoral descriptions of the world wealth distribution from 1 AD onwards.
5. The financial crisis and funding for college athletics.
"We found significant effects on depression at age 62 both for full-time workers who expected not to be working full-time, and for participants not working full-time who expected to be doing so. These results hold even after adjustment for earlier depressive symptoms, sociodemographic and other relevant controls. The findings suggest that working longer and retiring earlier than expected each may compromise psychological well-being. The current financial crisis may result in both scenarios as some workers may have to work longer than expected due to the decline in pension and other wealth while others may retire earlier due to job loss."
2. A fantastic back-and-forth between filmmaker Oliver Stone and venerable journalists Bob Woodward, Ron Suskund and Jacob Weisberg on Stone's new tragi-comic-biopic W and the Bush (II) presidency more generally. By the way, if you haven't seen W. yet, you should.
3. Dan Ariely presents evidence that conservatives may have a better sense of humor than liberals. Surprising? Not to me.
4. Chris Blattman on pictoral descriptions of the world wealth distribution from 1 AD onwards.
5. The financial crisis and funding for college athletics.
Thursday, October 23, 2008
Links on Early Life Origins of Health
1) Olivia Judson this week on the possible effects of early life influences (in particular maternal obesity and its affects on the fetus) on political behavior later in life (hat tip: Daniel Rothschild).
I'm glad to see this stuff in the popular press: some of my colleagues and I are looking at the influence of birth year and early childhood conditions on people's forward looking behavior, aversion to risk and expectations later in life, and pieces like this should whet the public's appetite! I'll be summarizing preliminary results of that research, as well as other work (including the early life effects on obesity) in a later post. Stay tuned.
2) In an earlier post, I briefly discussed a paper by Douglas Almond and Bhaskar Mazumdar about the negative effects of being in the womb during Ramadan on health outcomes later in life. A working version of the paper is now available via the NBER. The authors find these stunning results for two separate samples/populations: Arabs in Michigan and Muslims in Uganda.
3) But are early life influences quantitatively important in explaining trends in population health? Are such influences important levers for public policy? This recent Slate article suggests that the answer for both questions is "no." Here are two excerpts:
"The problem, though, is that large-scale problems also wrongly get blamed on the womb—and, by extension, on the woman who houses it. Womb-centric predictions of a child's future—whether rooted in supposed genetic disparities, gestational maternal-fetal conflict, eating habits during pregnancy, or whatever else—always undersell the role of one's later environment...
"Turning to the womb to explain complex social and public-health problems ultimately means people have given up on changing the things that really matter. That's too bad. The truth is that nothing in this world worth having comes easy. And as any hard-working student who made it to college, overweight person who's changed his or her lifestyle, or adult who's worked through depression can tell you, at some point you have to stop blaming your issues on your mother's uterus."
I think the author misfires on two of his (implicit) points. First, early life conditions do not occur deterministically. Public policy has tremendous scope to intervene into the health of pregnant women and newborns, and these interventions have been shown to have positive health and socioeconomic benefits both in the long-run and across generations. Second, while we can't retrospectively change what happened to a grown-up when he/she was in the womb, those experiences may still be important for the kinds of "here and now" interventions the author suggests we should focus on. For example, in my own work, I find that the body weight and blood pressure of individuals who experienced adverse economic shocks early in life is much more sensitive to food prices and income in comparison to those who did not.
Where I think the author does have a case is that we don't know for sure the extent to which these gestational and early childhood influences can explain cross-sectional and time-series trends in health outcomes. This is a question I am really interested in tackling, though I haven't really been able to get the data I need.
I'm glad to see this stuff in the popular press: some of my colleagues and I are looking at the influence of birth year and early childhood conditions on people's forward looking behavior, aversion to risk and expectations later in life, and pieces like this should whet the public's appetite! I'll be summarizing preliminary results of that research, as well as other work (including the early life effects on obesity) in a later post. Stay tuned.
2) In an earlier post, I briefly discussed a paper by Douglas Almond and Bhaskar Mazumdar about the negative effects of being in the womb during Ramadan on health outcomes later in life. A working version of the paper is now available via the NBER. The authors find these stunning results for two separate samples/populations: Arabs in Michigan and Muslims in Uganda.
3) But are early life influences quantitatively important in explaining trends in population health? Are such influences important levers for public policy? This recent Slate article suggests that the answer for both questions is "no." Here are two excerpts:
"The problem, though, is that large-scale problems also wrongly get blamed on the womb—and, by extension, on the woman who houses it. Womb-centric predictions of a child's future—whether rooted in supposed genetic disparities, gestational maternal-fetal conflict, eating habits during pregnancy, or whatever else—always undersell the role of one's later environment...
"Turning to the womb to explain complex social and public-health problems ultimately means people have given up on changing the things that really matter. That's too bad. The truth is that nothing in this world worth having comes easy. And as any hard-working student who made it to college, overweight person who's changed his or her lifestyle, or adult who's worked through depression can tell you, at some point you have to stop blaming your issues on your mother's uterus."
I think the author misfires on two of his (implicit) points. First, early life conditions do not occur deterministically. Public policy has tremendous scope to intervene into the health of pregnant women and newborns, and these interventions have been shown to have positive health and socioeconomic benefits both in the long-run and across generations. Second, while we can't retrospectively change what happened to a grown-up when he/she was in the womb, those experiences may still be important for the kinds of "here and now" interventions the author suggests we should focus on. For example, in my own work, I find that the body weight and blood pressure of individuals who experienced adverse economic shocks early in life is much more sensitive to food prices and income in comparison to those who did not.
Where I think the author does have a case is that we don't know for sure the extent to which these gestational and early childhood influences can explain cross-sectional and time-series trends in health outcomes. This is a question I am really interested in tackling, though I haven't really been able to get the data I need.
Thursday, October 16, 2008
I'm Fired!
My fantasy football team, following an almost miracle season, has regressed back to the mean this year. I am currently 2-4 and have the lowest point total of the 12 teams in our annual league. I attribute a lot of this to injuries: the three starting wide receivers I drafted are all out (two indefinitely and one for the year), as well as two of my defensive players. Furthermore, the league draft having been before the end of preseason, I found myself with two QBs with strong training-camp buzzes that turned out to be unusually poor forecasts. All in all, an idiosyncratic mess.
But, I look at my lifetime record (I average about a 6th place finish out of 12 teams) and realized that there is likely a persistent component to my lack of titles and general mediocrity. I also noticed that Yahoo! Fantasy Football has a new feature where people can co-manage a single fantasy team.
Given all this, I've decided to fire myself as the general manager of my team, and outsource the responsibilities of drafting and early season waiver-wire moves to someone else. I will still retain final authority over decision-making and retain the capacity to make some moves myself, but all of this will be in a much reduced role.
My firing of myself is effective immediately. I am currently looking for someone with at least five years of fantasy football experience (from competitive leagues, with a successful track record) to take over the GM role of the team. Let me know if you are interested.
But, I look at my lifetime record (I average about a 6th place finish out of 12 teams) and realized that there is likely a persistent component to my lack of titles and general mediocrity. I also noticed that Yahoo! Fantasy Football has a new feature where people can co-manage a single fantasy team.
Given all this, I've decided to fire myself as the general manager of my team, and outsource the responsibilities of drafting and early season waiver-wire moves to someone else. I will still retain final authority over decision-making and retain the capacity to make some moves myself, but all of this will be in a much reduced role.
My firing of myself is effective immediately. I am currently looking for someone with at least five years of fantasy football experience (from competitive leagues, with a successful track record) to take over the GM role of the team. Let me know if you are interested.
Wednesday, October 8, 2008
Random Thoughts from Cape Town
I have about two days left here in Cape Town and decided that this would be an appropriate time to reflect on what has been a great experience. I came here with the intention of finishing off one paper, and starting the second. As was the case with my last trip here, I leave the region with some great experiences and some new puzzles to ponder. Here are a collection of random thoughts I have (too tired to string these together in the usual thematic piece). Enjoy.
****
On the plane ride over, I saw this great movie called The Visitor. It's about a tenured widower academic (a development economist!) who is going through the motions in life, until he meets an illegal immigrant who he eventually shares his apartment with and starts learning the African drums from. The immigrant chap is eventually arrested and detained, and the academic works hard to get him out, forming life changing relationships with the drummer and the drummer's wife and mother in the process. It is an uplifting, sad and thoughtful movie, all at once, and perhaps one of the best movies I've seen in the last few months. Furthermore, Richard Jenkins, who plays the academic, gives an incredible performance and should win awards for this.
Highly recommended.
****
I absolutely love the University of Cape Town. Aside being located on the side of Table Mountain (and thus offering incredible views of both the mountain side and the city below), UCT is one of the best academic institutions on the continent, and the research that is going on here is really interesting. You often get a good grip on the quality of the research in an institution from the comments you get during a seminar. At my seminar, the feedback was ridiculously sharp and useful - definitely one of the best academic experiences of my young research career.
****
Speaking of UCT, I got a chance to revisit the owner of the Chinese food stall here, who made an appearance in one of my earlier posts on incentives to induce environmentally friendly behavior. The gentleman is still offering his R0.50 discount to those who bring their own plates or containers for food, though, he noted sadly, few people take him up on that these days. He seemed quite distraught to keep having to dole out styrofoam containers. I told him that it might be time to up the incentive, to which he laughed in response.
I don't think he is going to take me up on this.
****
One of the best ways to spend a day in Cape Town is to hike up Table Mountain and/or Lion's Head. Both offer stunning vistas of the city and surrounding suburbs. My body continues to revolt after the two hikes I've done here, but spending a day out in the sun, walking and climbing on paths surrounded by spring colors and geckos was pretty mind blowing.
Also mind blowing are Chandini restaurant in Woodstock (amazing Indian food), the Royale Eatery (at least 15 options for vegetarian burgers) and the High Life (Hare Krishna) food stall at UCT.
****
Of course, the trip wasn't all fun and games - at least in the recreational sense. My colleague and I spent most of our time working (fun and games, though of a different sort, in my book), and are onto some new research questions. In particular, we are going to look at links between economic vulnerability and shocks and risky sexual behaviors. More on that in a later post...
All in all, this has been a great trip: productive, fun, and thought-provoking. And it's been great also to create partnerships that could spur projects and travel opportunities in the future.
****
On the plane ride over, I saw this great movie called The Visitor. It's about a tenured widower academic (a development economist!) who is going through the motions in life, until he meets an illegal immigrant who he eventually shares his apartment with and starts learning the African drums from. The immigrant chap is eventually arrested and detained, and the academic works hard to get him out, forming life changing relationships with the drummer and the drummer's wife and mother in the process. It is an uplifting, sad and thoughtful movie, all at once, and perhaps one of the best movies I've seen in the last few months. Furthermore, Richard Jenkins, who plays the academic, gives an incredible performance and should win awards for this.
Highly recommended.
****
I absolutely love the University of Cape Town. Aside being located on the side of Table Mountain (and thus offering incredible views of both the mountain side and the city below), UCT is one of the best academic institutions on the continent, and the research that is going on here is really interesting. You often get a good grip on the quality of the research in an institution from the comments you get during a seminar. At my seminar, the feedback was ridiculously sharp and useful - definitely one of the best academic experiences of my young research career.
****
Speaking of UCT, I got a chance to revisit the owner of the Chinese food stall here, who made an appearance in one of my earlier posts on incentives to induce environmentally friendly behavior. The gentleman is still offering his R0.50 discount to those who bring their own plates or containers for food, though, he noted sadly, few people take him up on that these days. He seemed quite distraught to keep having to dole out styrofoam containers. I told him that it might be time to up the incentive, to which he laughed in response.
I don't think he is going to take me up on this.
****
One of the best ways to spend a day in Cape Town is to hike up Table Mountain and/or Lion's Head. Both offer stunning vistas of the city and surrounding suburbs. My body continues to revolt after the two hikes I've done here, but spending a day out in the sun, walking and climbing on paths surrounded by spring colors and geckos was pretty mind blowing.
Also mind blowing are Chandini restaurant in Woodstock (amazing Indian food), the Royale Eatery (at least 15 options for vegetarian burgers) and the High Life (Hare Krishna) food stall at UCT.
****
Of course, the trip wasn't all fun and games - at least in the recreational sense. My colleague and I spent most of our time working (fun and games, though of a different sort, in my book), and are onto some new research questions. In particular, we are going to look at links between economic vulnerability and shocks and risky sexual behaviors. More on that in a later post...
All in all, this has been a great trip: productive, fun, and thought-provoking. And it's been great also to create partnerships that could spur projects and travel opportunities in the future.
Tuesday, October 7, 2008
Circumcision, HAART and Behavior
Male circumcision is a hot topic among academics and policy-makers alike. A recent randomized controlled clinical trial suggests that the decrease in transmission rates from circumcision could rival those from putative AIDS vaccines (around a 60% in the odds of contracting HIV).
This is quite impressive, but, as my colleague Brendan here in Cape Town suggests, the public health benefits of a wide-scale circumcision program will likely be smaller than what is seen in clinical trials. The argument is that people will be encouraged to take up circumcision because it will lower their risk of contracting the disease. Men may who choose to get circumcised may then engage in more risky sexual behavior thereafter as a response to lower perceived risks, thus undoing some of the benefits of circumcision seen in the clinical evidence. The take home point is that policymakers should be careful when extrapolating from randomized clinical trials, and that behavioral responses to new public health policies may alter (sometimes radically) the efficacy of new interventions.
On a related note: an interesting piece from 2006 in the Quarterly Journal of Economics examines the effects of the development and roll-out of HAART on HIV incidence rates. The authors find that people on HAART take up more sexual partners as a result of being healthier. While the infectiousness of those on HAART is lower from those who are not treated, the authors contend that this phenomenon increases the risk of an HIV- individual contracting the disease: more HIV+ are engaged in sexual activity. They go on to argue that HAART may lower the welfare for those who are not infected with the virus. (Technical note: to establish causality, the authors use state-level differences in Medicaid generosity towards HAART to predict HAART use, and then use that predicted value in their models for risky behaviors).
This is quite impressive, but, as my colleague Brendan here in Cape Town suggests, the public health benefits of a wide-scale circumcision program will likely be smaller than what is seen in clinical trials. The argument is that people will be encouraged to take up circumcision because it will lower their risk of contracting the disease. Men may who choose to get circumcised may then engage in more risky sexual behavior thereafter as a response to lower perceived risks, thus undoing some of the benefits of circumcision seen in the clinical evidence. The take home point is that policymakers should be careful when extrapolating from randomized clinical trials, and that behavioral responses to new public health policies may alter (sometimes radically) the efficacy of new interventions.
On a related note: an interesting piece from 2006 in the Quarterly Journal of Economics examines the effects of the development and roll-out of HAART on HIV incidence rates. The authors find that people on HAART take up more sexual partners as a result of being healthier. While the infectiousness of those on HAART is lower from those who are not treated, the authors contend that this phenomenon increases the risk of an HIV- individual contracting the disease: more HIV+ are engaged in sexual activity. They go on to argue that HAART may lower the welfare for those who are not infected with the virus. (Technical note: to establish causality, the authors use state-level differences in Medicaid generosity towards HAART to predict HAART use, and then use that predicted value in their models for risky behaviors).
Friday, October 3, 2008
It's About Time
As of this past Wednesday, Medicare has stopped paying for procedures they deem to be the result of medical errors (great piece on it here). This was a long time coming. The hullabaloo around medical errors is now about a decade old, and several large private insurers in the interim realized the folly in paying doctors and hospitals to make mistakes. Glad to see the Feds followed suit.
I have a few questions though. This policy will only be effective if errors can be identified and there aren't other means the game the system. The new Medicare policy appears to hold up on the first ground (they have a list of specific things they won't pay for), but it is not clear to me that doctors or hospitals couldn't a) pass the costs on the patients or b) use different codes to procure payment. The linked article suggests that Medicare has a way around (a). I'd love to hear about it if any of you have more information.
This policy is a good idea from the standpoint that there are welfare losses due to medical errors and that people should never be paid for doing something wrong. On the flip side, my sense is that the impact of this policy on health care costs will be minimal, at best. The importance of medical errors as a money drain has long been overstated. It's nice to see the aforementioned popular press article get this point right.
I have a few questions though. This policy will only be effective if errors can be identified and there aren't other means the game the system. The new Medicare policy appears to hold up on the first ground (they have a list of specific things they won't pay for), but it is not clear to me that doctors or hospitals couldn't a) pass the costs on the patients or b) use different codes to procure payment. The linked article suggests that Medicare has a way around (a). I'd love to hear about it if any of you have more information.
This policy is a good idea from the standpoint that there are welfare losses due to medical errors and that people should never be paid for doing something wrong. On the flip side, my sense is that the impact of this policy on health care costs will be minimal, at best. The importance of medical errors as a money drain has long been overstated. It's nice to see the aforementioned popular press article get this point right.
Thursday, October 2, 2008
Incentives and HIV/AIDS
I'm now in Cape Town, South Africa, finishing off some research with my colleague Brendan Maughan-Brown and starting some fresh work, as well. It's definitely great to be back here, and away from the dissertation and financial crisis (kind of - the South African market went tumbling after the failure of the bailout, and my e-trade account looks destitute), if at least for a few days.
More so than usual, incentives and behavior have been front and center in my mind. Not surprising, as these topics figure centrally in a paper Brendan and I just presented and submitted for publication (see here for an earlier post on the topic). Some background: HIV/AIDS is a big problem in South Africa, with perhaps as much as 20% of the working age population afflicted by the disease. South African public policy towards the disease involves two main components: government provided antiretrovirals and disability grants. The latter is the focus of our work.
Disability grants are very large transfers given to poor individuals who are too sick to work. Once these individuals become healthy again, the grant is revoked. However, the problem in South Africa is that high rates of unemployment (up to 40% in some areas) make it likely that many individuals will not be able to find jobs post losing their grants. A fair amount of scholars and policy-wonks worry that this may create a perverse incentive for individuals to forego or modulate their antiretroviral treatment in order to remain eligible for grants.
We decided to investigate this issue by using some interesting data on individuals with HIV/AIDS taking treatment who were followed during the period 2004-2007. Our main finding is that, while losing a disability grant is associated with drops in individual and household income, people do not get sicker and continue to adhere to treatment. We find that households appear to use other strategies to cope with the loss of a grant, including transferring young children (dependents) to other households. In all of our models, we try to account for a host of factors that might bias our results (individuals on disability grants might be worse off because they need to meet a means test, or better off because they are good at pro-actively getting what they want or obtaining social transfers; the causality between the outcomes and disability grant receipt might run the other way, etc).
I'm not too surprised by these findings. It seems a bit much to think that someone who has been AIDS-sick would want to go through that again under any circumstances. In the words of a University of Cape Town researcher who attended the seminar Brendan and I gave: "being poor is better than being dead."
Another interesting thing we found was that individuals were receiving disability grants long after their eligibility should have been up (people on highly active antiretrovirals get better within six to nine months). This, along some other interesting evidence, leads us to believe that people are really good at gaming the social security system. So perhaps this is another reason why people aren't responding to the perverse incentive: there are other ways to survive (that confer far less risk and disutility), including taking advantage of a broken system.
Drop me a line if you have any questions about our work: I'm really excited about this project and the several extensions we have planned, and would certainly love to discuss.
More so than usual, incentives and behavior have been front and center in my mind. Not surprising, as these topics figure centrally in a paper Brendan and I just presented and submitted for publication (see here for an earlier post on the topic). Some background: HIV/AIDS is a big problem in South Africa, with perhaps as much as 20% of the working age population afflicted by the disease. South African public policy towards the disease involves two main components: government provided antiretrovirals and disability grants. The latter is the focus of our work.
Disability grants are very large transfers given to poor individuals who are too sick to work. Once these individuals become healthy again, the grant is revoked. However, the problem in South Africa is that high rates of unemployment (up to 40% in some areas) make it likely that many individuals will not be able to find jobs post losing their grants. A fair amount of scholars and policy-wonks worry that this may create a perverse incentive for individuals to forego or modulate their antiretroviral treatment in order to remain eligible for grants.
We decided to investigate this issue by using some interesting data on individuals with HIV/AIDS taking treatment who were followed during the period 2004-2007. Our main finding is that, while losing a disability grant is associated with drops in individual and household income, people do not get sicker and continue to adhere to treatment. We find that households appear to use other strategies to cope with the loss of a grant, including transferring young children (dependents) to other households. In all of our models, we try to account for a host of factors that might bias our results (individuals on disability grants might be worse off because they need to meet a means test, or better off because they are good at pro-actively getting what they want or obtaining social transfers; the causality between the outcomes and disability grant receipt might run the other way, etc).
I'm not too surprised by these findings. It seems a bit much to think that someone who has been AIDS-sick would want to go through that again under any circumstances. In the words of a University of Cape Town researcher who attended the seminar Brendan and I gave: "being poor is better than being dead."
Another interesting thing we found was that individuals were receiving disability grants long after their eligibility should have been up (people on highly active antiretrovirals get better within six to nine months). This, along some other interesting evidence, leads us to believe that people are really good at gaming the social security system. So perhaps this is another reason why people aren't responding to the perverse incentive: there are other ways to survive (that confer far less risk and disutility), including taking advantage of a broken system.
Drop me a line if you have any questions about our work: I'm really excited about this project and the several extensions we have planned, and would certainly love to discuss.
Thursday, September 18, 2008
Useful Links Re: Financial Crisis
The financial/credit crisis and our recent economic woes looms large in everyone's mind these days. Even in my counter-cyclical student bubble haven, there are daily reminders (both on the news and in the flesh) of people who have been hurt by the recent economic downturn (much more trivially, my own paltry investments have taken a huge hit these last 10 days, to the point where I've stopped logging into E-trade to view the carnage). All of this has deepened my resolve to try and understand how this crisis originated, how it can be prevented in the future, and what our country's economic prospects are for the next year or two.
My usual source for this kind of knowledge is The Economist. Lately though, I've found the stuff on the financial crisis to be a bit incomprehensible (is it just me or are they being a bit too jargony?). Thus, after a steady dose of the Englishmen, I felt up-to-date on all the news (like which bank went down most recently), but the hows and whys were still unclear.
Today, I did some browsing and found three pieces that really helped me gain a conceptual understanding about the financial system and what went wrong. The links are provided below. The first two couch the crisis in the form of hokey stories. It might seem a bit Mickey Mouse, but the insights are powerful and the analogies accessible. I would classify these as must reads for anyone who wants to understand what is going on without having to decipher all the usual Wall Street gibberish. The third is a guest post on the Freakonomics blog: also very good, and goes through the key questions and players and also provides some insights into what might happen in the future.
Finally, if any of you have found other sources/websites that explain the crisis in easy-to-understand terms, please post a link in the comments. Thanks in advance.
Links:
1. Interfluidity blog: Credit Crisis for Kindergarteners
2. CNN.com: Glenn Beck
3. Freakonomics: Diamond and Kashyap on the Recent Financial Upheavals
My usual source for this kind of knowledge is The Economist. Lately though, I've found the stuff on the financial crisis to be a bit incomprehensible (is it just me or are they being a bit too jargony?). Thus, after a steady dose of the Englishmen, I felt up-to-date on all the news (like which bank went down most recently), but the hows and whys were still unclear.
Today, I did some browsing and found three pieces that really helped me gain a conceptual understanding about the financial system and what went wrong. The links are provided below. The first two couch the crisis in the form of hokey stories. It might seem a bit Mickey Mouse, but the insights are powerful and the analogies accessible. I would classify these as must reads for anyone who wants to understand what is going on without having to decipher all the usual Wall Street gibberish. The third is a guest post on the Freakonomics blog: also very good, and goes through the key questions and players and also provides some insights into what might happen in the future.
Finally, if any of you have found other sources/websites that explain the crisis in easy-to-understand terms, please post a link in the comments. Thanks in advance.
Links:
1. Interfluidity blog: Credit Crisis for Kindergarteners
2. CNN.com: Glenn Beck
3. Freakonomics: Diamond and Kashyap on the Recent Financial Upheavals
Saturday, September 13, 2008
The Dubious Legacy of Candy Cigarettes?
I remember getting my first candy cigarette from a classmate at school when I was eight years old. I had no idea what it was, but it seemed pretty exciting and, despite my unusually high discount rate when it comes to candy (ask anyone in my family), I ended up saving it for when I got home.
This turned out to be a huge mistake. My mom saw me "smoking" and completely flipped out. From then on candy cigarettes were banned from my house (and, to this day, my mom gets mad if my sister and I pretend carrot sticks or pens to be cigarettes or cigars). Later, enough mothers were upset by the whole idea that candy cigarettes were banned from my elementary school, as well.
What worried moms across the country was the possibility that smoking candy cigarettes would induce children to take up the real thing a few years later. Is there good evidence that candy cigarette use has a causal effect on later smoking? I trolled around the internet and found some interesting links off the candy cigarettes Wikipedia page. As it turns out, there IS a study on the association between candy cigarette and nicotinic cigarette use (see here for a summary and here for the actual piece). Here are the findings (lifted from the abstract):
26.4% of respondents reported current smoking and 29.4% reported former smoking. Candy cigarette use was reported by 88% of both current and former smokers and 78% of never smokers (p ≤ 0.001). Logistic regression showed that the odds of smoking for those who used candy cigarettes was 1.98 (95% CI: 1.77, 2.21) for ever (current plus former) smokers and 1.83 (1.59, 2.10) for current smokers, compared to those who had not used candy cigarettes. Odds for current and ever smoking increased with increasing candy cigarette use.
The main issue here, of course, is whether the link between candy cigarettes and smoking is causal. For example, if individuals who really want to fit in use candy cigarettes to appear "cool" and later smoke for the same sense of social acceptance, one would see an association between the two behaviors, but this association certainly would not be causal. Even so, the results are pretty intriguing and worthy of further exploration.
This turned out to be a huge mistake. My mom saw me "smoking" and completely flipped out. From then on candy cigarettes were banned from my house (and, to this day, my mom gets mad if my sister and I pretend carrot sticks or pens to be cigarettes or cigars). Later, enough mothers were upset by the whole idea that candy cigarettes were banned from my elementary school, as well.
What worried moms across the country was the possibility that smoking candy cigarettes would induce children to take up the real thing a few years later. Is there good evidence that candy cigarette use has a causal effect on later smoking? I trolled around the internet and found some interesting links off the candy cigarettes Wikipedia page. As it turns out, there IS a study on the association between candy cigarette and nicotinic cigarette use (see here for a summary and here for the actual piece). Here are the findings (lifted from the abstract):
26.4% of respondents reported current smoking and 29.4% reported former smoking. Candy cigarette use was reported by 88% of both current and former smokers and 78% of never smokers (p ≤ 0.001). Logistic regression showed that the odds of smoking for those who used candy cigarettes was 1.98 (95% CI: 1.77, 2.21) for ever (current plus former) smokers and 1.83 (1.59, 2.10) for current smokers, compared to those who had not used candy cigarettes. Odds for current and ever smoking increased with increasing candy cigarette use.
The main issue here, of course, is whether the link between candy cigarettes and smoking is causal. For example, if individuals who really want to fit in use candy cigarettes to appear "cool" and later smoke for the same sense of social acceptance, one would see an association between the two behaviors, but this association certainly would not be causal. Even so, the results are pretty intriguing and worthy of further exploration.
Wednesday, September 10, 2008
Health Policy Seminar Series at Yale
If you are a Yale student or someone who happens to be visiting on a Monday between noon and 1:30 PM, be sure to check out this semester's Division of Health Policy and Administration's seminar series. The bill looks fantastic and represents a good mix of economics, health services research and management. It also features me, bringing up the tail end with a talk on a subject that is as of yet unknown (you'll hear more about it what I am doing in the next few weeks).
Hope to see you here!
Hope to see you here!
Tuesday, September 9, 2008
Public Nutrition Programs and Child Health
Two interesting working papers this week on the effect of major U.S. nutrition programs and child health. The first, by Douglas Almond and coauthors, examines the effect of the Food Stamp Program (FSP) on birth outcomes. Using variation in the roll-out of the program (Food Stamps became operative in different counties at different times during the 60s and 70s) to identify causal effects, the authors find that women exposed to the policy for three months or more of their pregnancy gave birth to heavier babies.
Daniel Millimet and coauthors study the School Breakfast Program (SBP) and the National School Lunch Program (NLSP), looking at the link between school feeding and childhood obesity. The authors find that the SBP works against the rising tide of childhood obesity while NSLP exacerbates it. Unfortunately, they offer little intuition for these opposing findings, especially when the two programs have similar inclusion criteria (i.e., they target poor students). One possibility might be the scope of the program: the NSLP serves twice as many students as the SBP. Another is the nutritional content of the meal: lunch is higher in calories (though similar in "healthiness").
Besides discussing issues of intrinsic interest to public health, these two papers are also noteworthy in their rigor in pursuing causal effects. The Millimet, et al study, in particular, uses a methodology where, recognizing that kids who enroll in SBP and NSLP are likely different than those who do not, they study the sensitivity of their results to different degrees of selection bias. Basically, the authors define a parameter for non-random selection into the program, and dial the level of this parameter up and down to see how their econometric results change. Very clever stuff. It's nice to see that, lacking experimental or even quasi-experimental program variation, such as that exploited in the Almond paper, it is still possible to say something about causality. The selection correction method utilized by Millimet, et al is simple and intuitive: I hope it finds it way into medical journals soon!
Daniel Millimet and coauthors study the School Breakfast Program (SBP) and the National School Lunch Program (NLSP), looking at the link between school feeding and childhood obesity. The authors find that the SBP works against the rising tide of childhood obesity while NSLP exacerbates it. Unfortunately, they offer little intuition for these opposing findings, especially when the two programs have similar inclusion criteria (i.e., they target poor students). One possibility might be the scope of the program: the NSLP serves twice as many students as the SBP. Another is the nutritional content of the meal: lunch is higher in calories (though similar in "healthiness").
Besides discussing issues of intrinsic interest to public health, these two papers are also noteworthy in their rigor in pursuing causal effects. The Millimet, et al study, in particular, uses a methodology where, recognizing that kids who enroll in SBP and NSLP are likely different than those who do not, they study the sensitivity of their results to different degrees of selection bias. Basically, the authors define a parameter for non-random selection into the program, and dial the level of this parameter up and down to see how their econometric results change. Very clever stuff. It's nice to see that, lacking experimental or even quasi-experimental program variation, such as that exploited in the Almond paper, it is still possible to say something about causality. The selection correction method utilized by Millimet, et al is simple and intuitive: I hope it finds it way into medical journals soon!
Thursday, September 4, 2008
Anyone Interesting in Working on a Small Project?
"Guess who's back, back again..."
That's right. I'm back to blogging after several weeks off - August turned out to be an exceptionally busy month (more on that in the next few days). It's great to come back to this space and resume writing about health economics and other topics of interest.
To start off September, I'd like to use this post to solicit help on a small project I am starting. Basically, I want to look at published studies of industry sponsorship bias in drug trials (a very hot topic: see here, from the recent issue of JAMA) and understand what we can learn with the existing statistical evidence, and need a research assistant to do some data collection and extraction. You will also be able to help out in designing the analysis. Here is what you get in return: authorship if the work gets published, and experience on what should be an interesting, fun, non-trivial and short project.
If you are interested in learning more, write me at this e-mail address.
Finally, I realize I'm being especially vague here about what the project is actually about. This is because I recently had a bad experience getting scooped and do not want to go through that again. However, you can trust me on the fact that this will, indeed, be interesting!
That's right. I'm back to blogging after several weeks off - August turned out to be an exceptionally busy month (more on that in the next few days). It's great to come back to this space and resume writing about health economics and other topics of interest.
To start off September, I'd like to use this post to solicit help on a small project I am starting. Basically, I want to look at published studies of industry sponsorship bias in drug trials (a very hot topic: see here, from the recent issue of JAMA) and understand what we can learn with the existing statistical evidence, and need a research assistant to do some data collection and extraction. You will also be able to help out in designing the analysis. Here is what you get in return: authorship if the work gets published, and experience on what should be an interesting, fun, non-trivial and short project.
If you are interested in learning more, write me at this e-mail address.
Finally, I realize I'm being especially vague here about what the project is actually about. This is because I recently had a bad experience getting scooped and do not want to go through that again. However, you can trust me on the fact that this will, indeed, be interesting!
Thursday, July 31, 2008
Work Hour Limitations for Interns and Residents: Good or Bad for Patients?
A great piece by Sandeep Jauhar in Slate explores the effects of work hour limitations for medical residents on patient care. The article highlights trade-offs inherent in these policies. On the one hand, sleepy residents make more mistakes. On the other, work restrictions that reduce the total number of hours worked among all residents encourage the use of cross-cover mechanisms (the article talks a lot about night float) which may reduce the continuity of care. This, too, may adversely affect patient care if continuity is important. As Jauhar points out, the ultimate impact of work hour restrictions comes down to an empirical question, and the available evidence appears mixed.
The discontinuous introduction of residency work hour restrictions nationwide, as well as the random assignment of interns and residents to regular and night-float shifts, can be exploited to study the impact of both work hour restrictions as well as different cross-cover mechanisms. With such a transparent identification strategy available, I'm surprised that only two major studies have been done on this issue (even more so since the meta-evidence is inconclusive). Perhaps it is difficult to find data on outcomes or on how the time of residents is allocated?
I'd be curious to start looking at some new data on this if anyone is interested.
The discontinuous introduction of residency work hour restrictions nationwide, as well as the random assignment of interns and residents to regular and night-float shifts, can be exploited to study the impact of both work hour restrictions as well as different cross-cover mechanisms. With such a transparent identification strategy available, I'm surprised that only two major studies have been done on this issue (even more so since the meta-evidence is inconclusive). Perhaps it is difficult to find data on outcomes or on how the time of residents is allocated?
I'd be curious to start looking at some new data on this if anyone is interested.
Tuesday, July 29, 2008
Air Pollution and Infant Health
A recent working paper by Janet Currie and collaborators finds the following:
We examine the impact of three "criteria" air pollutants on infant health in New Jersey in the 1990s by combining information about mother's residential location from birth certificates with information from air quality monitors. In addition to large sample size, our work offers three important innovations: First, because we know the exact addresses of mothers, we select those mothers closest to air monitors to ensure a more accurate measure of air quality. Second, since we follow mothers over time, we control for unobserved characteristics of mothers using maternal fixed effects. Third, we examine interactions of air pollution with smoking and other predictors of poor infant health outcomes. We find consistently negative effects of exposure to pollution, especially carbon monoxide, both during and after birth. The effects are considerably larger for smokers than for nonsmokers as well as for older mothers. Since automobiles are the main source of carbon monoxide emissions, our results have important implications for regulation of automobile emissions.
See here for an earlier post on the subject, discussing a paper looking at the relationship between pollution from forest fires and infant mortality.
We examine the impact of three "criteria" air pollutants on infant health in New Jersey in the 1990s by combining information about mother's residential location from birth certificates with information from air quality monitors. In addition to large sample size, our work offers three important innovations: First, because we know the exact addresses of mothers, we select those mothers closest to air monitors to ensure a more accurate measure of air quality. Second, since we follow mothers over time, we control for unobserved characteristics of mothers using maternal fixed effects. Third, we examine interactions of air pollution with smoking and other predictors of poor infant health outcomes. We find consistently negative effects of exposure to pollution, especially carbon monoxide, both during and after birth. The effects are considerably larger for smokers than for nonsmokers as well as for older mothers. Since automobiles are the main source of carbon monoxide emissions, our results have important implications for regulation of automobile emissions.
See here for an earlier post on the subject, discussing a paper looking at the relationship between pollution from forest fires and infant mortality.
Wednesday, July 23, 2008
Do Better Trained Physicians Provide Better Care?
A while back, I blogged about how medical care varies in quality and quantity across different areas in the United States, as well as the reasons why such "small area variation" might exist. This post looks at the same topic but from a slightly different perspective: to what extent can differences in physician quality (where they were trained and where they currently work) explain the variance in medical care seen across groups of patients and regions?
This isn't an easy question to answer: getting at causal effects of physician quality is really hard. For example, an association between patient outcomes and physician quality could simply reflect the fact that wealthier or smarter patients, who are better able to translate directions from their physician to better health outcomes, happen to choose better doctors themselves. As such, conventional estimates using observational data may be biased.
In a very clever study, Joseph Doyle and co-authors get around this selection issue using a natural experiment methodology. In particular, they utilize the randomization of patients in the Veterans Affairs (VA) system to clinical teams from two academic medical centers. One center happens to be very highly rated and the other not so much. Their results suggest that physician quality matters in terms of costs and length of stay, though not so much for ultimate health outcomes:
Those treated by physicians from the higher-ranked institution have 10-25% shorter and less expensive stays than patients assigned to the lower-ranked institution. Health outcomes are not related to the physician team assignment, and the estimates are precise. Procedure differences across the teams are consistent with the ability of physicians in the lower-ranked institution to substitute time and diagnostic tests for the faster judgments of physicians from the top-ranked institution.
Interesting stuff.
This isn't an easy question to answer: getting at causal effects of physician quality is really hard. For example, an association between patient outcomes and physician quality could simply reflect the fact that wealthier or smarter patients, who are better able to translate directions from their physician to better health outcomes, happen to choose better doctors themselves. As such, conventional estimates using observational data may be biased.
In a very clever study, Joseph Doyle and co-authors get around this selection issue using a natural experiment methodology. In particular, they utilize the randomization of patients in the Veterans Affairs (VA) system to clinical teams from two academic medical centers. One center happens to be very highly rated and the other not so much. Their results suggest that physician quality matters in terms of costs and length of stay, though not so much for ultimate health outcomes:
Those treated by physicians from the higher-ranked institution have 10-25% shorter and less expensive stays than patients assigned to the lower-ranked institution. Health outcomes are not related to the physician team assignment, and the estimates are precise. Procedure differences across the teams are consistent with the ability of physicians in the lower-ranked institution to substitute time and diagnostic tests for the faster judgments of physicians from the top-ranked institution.
Interesting stuff.
Tuesday, July 22, 2008
Contest Winners
Hi all. This summer's 'Dar he Blogs winners are Christi H and James Hudspeth, for the professional eating and p-value contests, respectively. I thought Christi's answer really hit it on all cylinders as far as pointing out the physical and mental strength required to succeed in competitive eating. James ran unopposed in his contest. While I didn't quite get the answer I wanted, he did alert me to "The Lady Tasting Tea," which is turning out to be a great book (anyone interested in a breezy account of how statistics has contributed to the practice of science in the 20th century must absolutely read this book!).
Christi and James: Congrats, and get in touch with me about your prize, which will be a popular economics book of your choice.
Christi and James: Congrats, and get in touch with me about your prize, which will be a popular economics book of your choice.
Thursday, July 17, 2008
Contest Reminder!
You have until Saturday (the 19th) morning to submit your entries for the "Competitive Eating" and "P-value" contests. The prizes are excellent and are outlined in the second link (and see here for proof that I actually deliver on the prizes).
Bring it.
Bring it.
Tuesday, July 15, 2008
Economics of Love
A good friend, Rucheeta Kulkarni, sent me this interesting piece by Ben Stein. My sense is that it takes basic (I mean, VERY basic) concepts from neoclassical theory to generate some insights on how to approach relationships.
One thing I'd like to see is parallel piece from the standpoint of behavioral economics. Many people systematically DO NOT follow Stein's advice and it would be worth understanding (the patterns underlying) why. Hmmm....now THAT would make for a good column in Cosmo, Maxim, etc.
One thing I'd like to see is parallel piece from the standpoint of behavioral economics. Many people systematically DO NOT follow Stein's advice and it would be worth understanding (the patterns underlying) why. Hmmm....now THAT would make for a good column in Cosmo, Maxim, etc.
Wednesday, July 9, 2008
Corruption in India
Neil Vaishnavi (of Wash U fame) sent me this interesting article from CNN on corruption in India. The main thrust is that a third of individuals below the poverty line pay bribes in order "to file a police report, to enroll a child in school, to admit a family member into a hospital or to get electricity turned on." All of these are public services that are theoretically provided free of charge. Regarding hospitals more specifically, a 2005 report from Transparency International India suggests that corruption, on a per visit basis, is most rampant here, in comparison to other institutions such as schools.
There are two questions that arise when thinking about corruption. First, is it efficient? Does corruption sufficiently grease the wheels and create an effective price in markets with artificial price ceilings? Or do the negatives of corruption outweigh these positive effects. See here for a great discussion, peppered with some experimental evidence from India.
Another question: who bears the larger burden of corruption - the rich or the poor? There a two ways to look at this. The first is in the strict income sense: does the fraction of one's income allocated to bribes vary for the rich vis-a-vis the poor? Or is the marginal bribe dollar or rupee more valuable to one socioeconomic group or the other? The latter question gets at the second issue: do rich willingly pay bribes out of convenience, whereas the poor are coerced? As mentioned in an earlier post, Paul Lagunes, Brian Fried (both of the Yale Political Science department) and I tried to get at this with an audit study of traffic officers in Latin America. We fix the interactions so as to rule out the convenience story and found that traffic officers more frequently targeted lower class drivers for bribes than their upper class counterparts. The expected bribe payment appeared to be the same across both groups, which leads us to believe that corruption, at least in this context, might be regressive.
There are two questions that arise when thinking about corruption. First, is it efficient? Does corruption sufficiently grease the wheels and create an effective price in markets with artificial price ceilings? Or do the negatives of corruption outweigh these positive effects. See here for a great discussion, peppered with some experimental evidence from India.
Another question: who bears the larger burden of corruption - the rich or the poor? There a two ways to look at this. The first is in the strict income sense: does the fraction of one's income allocated to bribes vary for the rich vis-a-vis the poor? Or is the marginal bribe dollar or rupee more valuable to one socioeconomic group or the other? The latter question gets at the second issue: do rich willingly pay bribes out of convenience, whereas the poor are coerced? As mentioned in an earlier post, Paul Lagunes, Brian Fried (both of the Yale Political Science department) and I tried to get at this with an audit study of traffic officers in Latin America. We fix the interactions so as to rule out the convenience story and found that traffic officers more frequently targeted lower class drivers for bribes than their upper class counterparts. The expected bribe payment appeared to be the same across both groups, which leads us to believe that corruption, at least in this context, might be regressive.
Sunday, July 6, 2008
The One Year Mark
Today marks the 1 year anniversary of 'Dar he blogs. I just wanted to thank everyone for reading and for posting such thoughtful comments. This whole outfit started as a travel blog, but now has taken on a life of its' own. I definitely plan on continuing the blog for at least another year.
Anyhow, I've had a lot of fun doing this, and I hope you've enjoyed the blog, too. Thanks again for reading.
Anyhow, I've had a lot of fun doing this, and I hope you've enjoyed the blog, too. Thanks again for reading.
Friday, July 4, 2008
Contest: Is Professional Eating a Sport?
Along with America's birthday (though not really?), July 4th is also home to another fun spectacle: the Nathan's Famous Hot Dog Eating Contest. For those of you not in the know, the winner of the contest is the man or woman who can eat the most buns and franks in a 12 minute span. In recent years, this contest has been dominated by Takeru Kobeyashi, a Japanese man who looks more like an ultimate fighter contestant than someone who is capable of packing in 60 buns and franks in 12 minutes. In 2007, after winning six Nathan's contests in a row, Kobeyashi was upended by American Joey "Jaws" Chestnut, 66 - 63. Prior to this defeat, the string of victories led some observers to suggest that Kobeyashi was, relative to his sport, the greatest and most dominant athlete in the world.
And herein lies the motivation for this contest: is professional eating a "real" sport? Whoever makes the best argument for or against will receive a prize (details here, which also links you to my other summer contest). As always, the only parameters for the prize winning entry is that I have to like it, so you are open to argue by induction, analogy, contradiction, whatever. Please leave your entry as a comment; the contest closes two weeks from today.
Finally, be sure to watch the 2008 Nathan's contest, noon eastern on ESPN.
And herein lies the motivation for this contest: is professional eating a "real" sport? Whoever makes the best argument for or against will receive a prize (details here, which also links you to my other summer contest). As always, the only parameters for the prize winning entry is that I have to like it, so you are open to argue by induction, analogy, contradiction, whatever. Please leave your entry as a comment; the contest closes two weeks from today.
Finally, be sure to watch the 2008 Nathan's contest, noon eastern on ESPN.
Wednesday, July 2, 2008
Alcohol Use and Mortality in Mexico
There is a well-crafted and important paper by Gretchen Stevens and coauthors on the leading causes of death and their attributable factors in Mexico in the June 2008 issue of PLoS Medicine. Here's the punchline:
Mexico is at an advanced stage in the epidemiologic transition, with the majority of the disease and injury burden from noncommunicable diseases. A unique characteristic of the epidemiological transition in Mexico is that overweight and obesity, high blood glucose, and alcohol use are responsible for larger burden of disease than other noncommunicable disease risks such as tobacco smoking. The Southern region is least advanced in the epidemiological transition and suffers from the largest burden of ill health in all disease and injury groups.
Alcohol use holds the plurality share of all deaths among men, with obesity and high blood glucose (separately) close behind. This is certainly different than the pattern in the United States: alcohol abuse comes in a fairly distant third behind tobacco use and diet/physical inactivity. Myself and several others I spoke to regarding this were rather surprised by the Mexican statistics: we hear so much about Mexico being on its way becoming the world's fattest nation, but little about its' alcohol use. Perhaps another example of a single issue hijacking the policy agenda?
Interestingly, alcohol use appears to be responsible for a non-trivial percentage of female deaths as well (though this number is well below obesity and associated metabolic conditions). Sadly, the authors of the paper point out that much of it may be secondary to abuse from men who abuse alcohol.
As with the literature in the United States, I wonder if there are studies using Mexican data that use time and cross-sectional variation in alcohol laws to identify the causal impacts of public policy (via alcohol use) on domestic violence, crime, etc. A quick Google search on this revealed little. However, I did find this interesting piece by Manuela Angelucci, examining the relationship between income and alcohol use and use related violence towards women. To identify the causal effect of income, the paper uses shocks from (then) randomly assigned access to the Oportunidades conditional cash transfer program (which pay women for meeting targets in child and household health, education, etc) and weather and natural disaster shocks that affect rural households. She finds that the marginal peso accruing to women leads to significant decreases in their partners' alcohol use and violent behavior. The effect of a shock to the partners income is minimal. Yet another good example of why public transfers of cash to women accrues much greater benefits to households than does targeting men.
Mexico is at an advanced stage in the epidemiologic transition, with the majority of the disease and injury burden from noncommunicable diseases. A unique characteristic of the epidemiological transition in Mexico is that overweight and obesity, high blood glucose, and alcohol use are responsible for larger burden of disease than other noncommunicable disease risks such as tobacco smoking. The Southern region is least advanced in the epidemiological transition and suffers from the largest burden of ill health in all disease and injury groups.
Alcohol use holds the plurality share of all deaths among men, with obesity and high blood glucose (separately) close behind. This is certainly different than the pattern in the United States: alcohol abuse comes in a fairly distant third behind tobacco use and diet/physical inactivity. Myself and several others I spoke to regarding this were rather surprised by the Mexican statistics: we hear so much about Mexico being on its way becoming the world's fattest nation, but little about its' alcohol use. Perhaps another example of a single issue hijacking the policy agenda?
Interestingly, alcohol use appears to be responsible for a non-trivial percentage of female deaths as well (though this number is well below obesity and associated metabolic conditions). Sadly, the authors of the paper point out that much of it may be secondary to abuse from men who abuse alcohol.
As with the literature in the United States, I wonder if there are studies using Mexican data that use time and cross-sectional variation in alcohol laws to identify the causal impacts of public policy (via alcohol use) on domestic violence, crime, etc. A quick Google search on this revealed little. However, I did find this interesting piece by Manuela Angelucci, examining the relationship between income and alcohol use and use related violence towards women. To identify the causal effect of income, the paper uses shocks from (then) randomly assigned access to the Oportunidades conditional cash transfer program (which pay women for meeting targets in child and household health, education, etc) and weather and natural disaster shocks that affect rural households. She finds that the marginal peso accruing to women leads to significant decreases in their partners' alcohol use and violent behavior. The effect of a shock to the partners income is minimal. Yet another good example of why public transfers of cash to women accrues much greater benefits to households than does targeting men.
Saturday, June 28, 2008
ASHE Conference Recap - Part II
I've devoted a non-trivial chunk of this space to talking about how events and shocks that influence the nutritional intake and disease status in utero and during the early childhood years may play a large role in determining the health, education, earnings, and general well-being later in life. Research on the early life origins of disease and poverty has become popular in economics, as evidenced by the number of studies on this topic presented at the ASHE conference.
While all of these papers were interesting, four stood out:
1) Marten Lindeboom and colleagues looked at the impact of the 1846-47 Dutch Potato Famine on subsequent mortality risk. Their research strategy was to use the discontinuous timing of the famine, to compare cohorts in utero during the famine to those born just before and just after this period. They find strong links between famine exposure and mortality risk for men aged 50 and above, but not for women. These results are consistent with biological theories that posit that males are more vulnerable to shocks early in life than females.
2) Martin Salm, my discussant at the conference, presented some interesting work on the extent to which health contributes to the link between socioeconomic status across generations. Martin and his coauthor found that 20-30% of the correlation between parental education and child cognitive skills can be explained by childhood health conditions.
3) Tania Barham examined the effect of health interventions in Bangladesh, in particular the staggered introduction of child vaccination programs in the 1980s, on cognitive development. Using this variation, along with mother fixed effects, she finds strong links between early life exposure to these public health programs and the child's mini-mental state exam scores later in life.
4) Daniel Rees and Joseph Sabia studied the causal effect of breastfeeding on academic achievement. To get at causal inference, they utilize the variation in breastfeeding across the children of a given mother, with the assumption being that, conditional on the mother and a rich set of control for other child-specific prenatal and postnatal behaviors, this variation is essentially exogenous with respect to outcomes of interest. They find strong effects of breastfeeding on later outcomes.
------------------------------------------
Behavioral economics, also an oft discussed subject in this blog, was also on display at the ASHE conference. Jody Sindelar, who happens to be my dissertation supervisor, gave a fantastic talk on the importance of behavioral economics to health economics. Mainstream microeconomics rests on the neoclassical model, where individuals rationally calculate all (discounted) costs and benefits before making a decision. The feeling among many economists is that the workhorse neoclassical models do pretty well in explaining most phenomena, and that behavioral economics is a fun curiousity with limited policy interest.
Jody's talk served as a reminder that, especially in health care, behavioral economics may offer important policy relevant insights. Of the series of interesting examples she presented, my favorite was from international organ donation rates: countries with presumed consent legislation (i.e., you have to opt-out to get out of donating your organs) have higher rates of donation that those with opt-in laws (i.e., you have to give someone permission to take your organs). Neoclassical economics doesn't quite explain this; behavioral economics does. The policy significance of some extra organs for extremely thin organ markets is quite large.
Brian Elbel, a graduate from my program at Yale and now a professor at NYU, gave an interesting talk on his experimental work studying the behavioral economics of choosing a Medicare managed care plan. Briefly, Brian found that consumers tend make suboptimal choices regarding their health care plans, or defer these choices altogether, when presented with a larger number of options (which is antithetical to neoclassical theories predicting increased efficiency with greater choice) and when bad options are presented along with good ones. His experimental evidence, along with his econometric evidence from another paper, suggest the power of behavioral economics in explaining choices related to a very important government program.
---------------------------------------
The final plenary session at the conference was given by Gary Becker, a Nobel laureate who revolutionized economics by extending the field to the analysis of phenomena like childbearing, child investments, polygamy, crime, discrimination, etc. (He's also a fine blogger: check out the Becker-Posner blog in the links sidebar). Becker's talk was based on his latest research, looking at the total returns to education. The basic idea was that economists have focused greatly on the wage returns to education. However, the value of education likely goes well beyond wages: a slew of studies have shown strong correlations between an individual's education and his/her health, happiness, the probability of marriage and the "quality" of spouse, and the educational attainment and health of his/her children.
Becker's talk focused on an interesting puzzle: the recent boom in college education. More people in the U.S., especially women, are attending and completing college as opposed to even 15-20 years ago. Becker suggested that such a boom is likely driven by changes in the returns to education. As such, Becker investigated where the growth in the returns to college might be coming from. My favorite slide in the presentation showed the marriage probabilities of women as a function of high school, college, and post-graduate education. In the 1960s, women with graduate degrees were much less likely to get married their those women who finished high school or college. Today, the relationship between marriage probabilities and the woman's level of education is monotone increasing across all levels of education!
Another interesting puzzle from the Becker talk: if college education has such high total returns, why don't more people take the meal ticket? Becker commented that this is a question he is currently struggling with and that perhaps those who end up finding an answer to this would themselves win a Nobel prize. In a room with nearly a thousand health economists, I saw at least half instinctively lurch for their pens and notebooks as soon as he said this!
While all of these papers were interesting, four stood out:
1) Marten Lindeboom and colleagues looked at the impact of the 1846-47 Dutch Potato Famine on subsequent mortality risk. Their research strategy was to use the discontinuous timing of the famine, to compare cohorts in utero during the famine to those born just before and just after this period. They find strong links between famine exposure and mortality risk for men aged 50 and above, but not for women. These results are consistent with biological theories that posit that males are more vulnerable to shocks early in life than females.
2) Martin Salm, my discussant at the conference, presented some interesting work on the extent to which health contributes to the link between socioeconomic status across generations. Martin and his coauthor found that 20-30% of the correlation between parental education and child cognitive skills can be explained by childhood health conditions.
3) Tania Barham examined the effect of health interventions in Bangladesh, in particular the staggered introduction of child vaccination programs in the 1980s, on cognitive development. Using this variation, along with mother fixed effects, she finds strong links between early life exposure to these public health programs and the child's mini-mental state exam scores later in life.
4) Daniel Rees and Joseph Sabia studied the causal effect of breastfeeding on academic achievement. To get at causal inference, they utilize the variation in breastfeeding across the children of a given mother, with the assumption being that, conditional on the mother and a rich set of control for other child-specific prenatal and postnatal behaviors, this variation is essentially exogenous with respect to outcomes of interest. They find strong effects of breastfeeding on later outcomes.
------------------------------------------
Behavioral economics, also an oft discussed subject in this blog, was also on display at the ASHE conference. Jody Sindelar, who happens to be my dissertation supervisor, gave a fantastic talk on the importance of behavioral economics to health economics. Mainstream microeconomics rests on the neoclassical model, where individuals rationally calculate all (discounted) costs and benefits before making a decision. The feeling among many economists is that the workhorse neoclassical models do pretty well in explaining most phenomena, and that behavioral economics is a fun curiousity with limited policy interest.
Jody's talk served as a reminder that, especially in health care, behavioral economics may offer important policy relevant insights. Of the series of interesting examples she presented, my favorite was from international organ donation rates: countries with presumed consent legislation (i.e., you have to opt-out to get out of donating your organs) have higher rates of donation that those with opt-in laws (i.e., you have to give someone permission to take your organs). Neoclassical economics doesn't quite explain this; behavioral economics does. The policy significance of some extra organs for extremely thin organ markets is quite large.
Brian Elbel, a graduate from my program at Yale and now a professor at NYU, gave an interesting talk on his experimental work studying the behavioral economics of choosing a Medicare managed care plan. Briefly, Brian found that consumers tend make suboptimal choices regarding their health care plans, or defer these choices altogether, when presented with a larger number of options (which is antithetical to neoclassical theories predicting increased efficiency with greater choice) and when bad options are presented along with good ones. His experimental evidence, along with his econometric evidence from another paper, suggest the power of behavioral economics in explaining choices related to a very important government program.
---------------------------------------
The final plenary session at the conference was given by Gary Becker, a Nobel laureate who revolutionized economics by extending the field to the analysis of phenomena like childbearing, child investments, polygamy, crime, discrimination, etc. (He's also a fine blogger: check out the Becker-Posner blog in the links sidebar). Becker's talk was based on his latest research, looking at the total returns to education. The basic idea was that economists have focused greatly on the wage returns to education. However, the value of education likely goes well beyond wages: a slew of studies have shown strong correlations between an individual's education and his/her health, happiness, the probability of marriage and the "quality" of spouse, and the educational attainment and health of his/her children.
Becker's talk focused on an interesting puzzle: the recent boom in college education. More people in the U.S., especially women, are attending and completing college as opposed to even 15-20 years ago. Becker suggested that such a boom is likely driven by changes in the returns to education. As such, Becker investigated where the growth in the returns to college might be coming from. My favorite slide in the presentation showed the marriage probabilities of women as a function of high school, college, and post-graduate education. In the 1960s, women with graduate degrees were much less likely to get married their those women who finished high school or college. Today, the relationship between marriage probabilities and the woman's level of education is monotone increasing across all levels of education!
Another interesting puzzle from the Becker talk: if college education has such high total returns, why don't more people take the meal ticket? Becker commented that this is a question he is currently struggling with and that perhaps those who end up finding an answer to this would themselves win a Nobel prize. In a room with nearly a thousand health economists, I saw at least half instinctively lurch for their pens and notebooks as soon as he said this!
Thursday, June 26, 2008
ASHE Conference Recap - Part I
I just got back from the 2008 ASHE conference (see previous post) at Duke University. I had an absolutely stellar time. In fact, I'd say I got a lot more out of this conference than from those in the past. I think this has a lot to do with the fact that:
1) Having been to all those previous conferences, I actually knew people at this one. Not only is it fun to catch up with old friends, but having old friends makes it easier to make new ones.
2) I have a better sense of what I am interested in, so I can self-select into sessions that will better satisfy my curiousity.
3) The average presentation at ASHE was high quality and the conference was well-attended by the field's superstars.
4) My presentation went really well and was well received.
5) The conference was at Duke, my alma mater. I ended up taking my first economics class, taught by Allen Kelley, on a lark, which, along with two other Allen Kelley classes, planted the seeds for my decision to take up a PhD a few years later.
---------------------
Some broad themes from the conference. The sessions started with a keynote address by Mark McClellan, an MD/PhD economist with strong academic and policy credentials (he was in charge of the Centers for Medicare and Medicaid Services and the FDA), along with a now (in)famous brother. The basic theme of the talk was how health economics can help with policymaking, especially with an impending new administration. While it was exciting to hear that policy-makers are begging for policy-relevant evidence from health economists, it was depressing to hear that, despite nearly forty years of health economics, officials at the CBO and OMB are still forced to write sentences like "Evidence on the effectiveness of this intervention is inconsistent and limited" when trying to score new public health and health care policies.
Indeed, I saw this with my own eyes when contemplating the sum evidence from the numerous sessions on obesity. The papers therein covered a wide range of topics: the effects of food and drink prices, fast foods, law changes, and education on obesity; the impact of obesity on academic achievement and labor market earnings; and the economic costs of obesity. Each of these topics requires some heavy statistical lifting to get around the obvious causal inference issues. All of the conference papers came armed with the latest techniques. However, the sum knowledge from the slew of studies, in terms of policy relevance, appears to be limited. For example, the papers collectively suggested that food prices, fast foods, taxes and law changes appear to have only modest effects on obesity prevalence. As such policies centered around these factors, such as the popular "fast food tax" may lack heft as useful public health instruments.
--------------------
Since, I mentioned methods, I should point out that it was heartening to see such a high level of scientific rigor at these meetings. There was a healthy obsession with causal inference, and nearly all of the papers used fixed effects or instrumental variables. For those who are not into the jargon, fixed effects is best explained by an example: imagine you have data following the same individuals over time. You are interested in learning the effect of some X on Y, but are worried about bias from some omitted variable U, a characteristic about the individual. Fixed effects allow you to essentially subtract of the individual level mean from X and Y. If U doesn't vary across individuals, fixed effects basically washes this confounder out of the estimation procedure. Now you can get at the causal effect X on Y.
Sibling or twin studies are a good example of fixed effects. Let's say you want to learn the causal effects of birthweight on later wages. The worry is that birthweight is correlated with genetic factors or socioeconomic status early in life, which is correlated with outcomes later in adulthood. Using twin fixed effects, you can control for (or difference out) for genes and shared early life socieconomic status.
Of course, if the omitted variables that you worry about change over time for an individual or vary across a set of siblings, fixed effects estimates will not recover causal effects. To get around this researchers often use instrumental variable (IV) methods (either alone or in conjunction with fixed effects), where a factor that affects the regressor of interest, but not the outcome directly or indirectly through some other factor, is used to identify causal impacts. A famous example is the use of the quarter of birth or school cutoff dates to predict attained schooling (individuals born later and near the cutoff date are younger when they finish schooling or a full grade behind when they drop out).
The validity and theoretical basis for instruments are hotly debated, and researchers now must meet a pretty heavy burden of proof to get people interested and convinced. Also, it is now well-known that instruments must predict the regressor of interest strongly enough so as to yield valid estimates: "weak" instruments lead to biases of their own. It was nice to see that researchers at the conference went into great detail when defending their assumptions underlying the use of fixed effects and instruments. It was also nice to see the discussants call these assumptions into question and pointing out the additional implicit assumptions that needed to be made to achieve validity. This sort of discussion forces people to write down an explicit model and all the required identifying assumptions.
At some point though, I couldn't help but feel like there was some overkill and overpolicing, especially with the weak instruments issue (one researcher with a good IV strategy commented that she did not utilize the approach because her instruments were slightly weaker than what is considered kosher). Some new research on IV points suggests the use of estimation techniques that are robust to weak instruments: I was surprised that more conference-goers had not adopted these (indeed, mine was the only paper I saw that used these techniques). Second, some recent research suggests ways to proceed with instruments that might be "slightly" correlated with unobserved factors that influence the outcome and to test the sensitivity of IV results to varying degrees of instrument "badness." I would have liked to have seen a higher rate of adoption of these new techniques.
---------------------------------
In the next installment, I'll speak more about my ASHE experiences by summarizing some research on the early life origins of disease, behavioral economics, and the many benefits of education.
1) Having been to all those previous conferences, I actually knew people at this one. Not only is it fun to catch up with old friends, but having old friends makes it easier to make new ones.
2) I have a better sense of what I am interested in, so I can self-select into sessions that will better satisfy my curiousity.
3) The average presentation at ASHE was high quality and the conference was well-attended by the field's superstars.
4) My presentation went really well and was well received.
5) The conference was at Duke, my alma mater. I ended up taking my first economics class, taught by Allen Kelley, on a lark, which, along with two other Allen Kelley classes, planted the seeds for my decision to take up a PhD a few years later.
---------------------
Some broad themes from the conference. The sessions started with a keynote address by Mark McClellan, an MD/PhD economist with strong academic and policy credentials (he was in charge of the Centers for Medicare and Medicaid Services and the FDA), along with a now (in)famous brother. The basic theme of the talk was how health economics can help with policymaking, especially with an impending new administration. While it was exciting to hear that policy-makers are begging for policy-relevant evidence from health economists, it was depressing to hear that, despite nearly forty years of health economics, officials at the CBO and OMB are still forced to write sentences like "Evidence on the effectiveness of this intervention is inconsistent and limited" when trying to score new public health and health care policies.
Indeed, I saw this with my own eyes when contemplating the sum evidence from the numerous sessions on obesity. The papers therein covered a wide range of topics: the effects of food and drink prices, fast foods, law changes, and education on obesity; the impact of obesity on academic achievement and labor market earnings; and the economic costs of obesity. Each of these topics requires some heavy statistical lifting to get around the obvious causal inference issues. All of the conference papers came armed with the latest techniques. However, the sum knowledge from the slew of studies, in terms of policy relevance, appears to be limited. For example, the papers collectively suggested that food prices, fast foods, taxes and law changes appear to have only modest effects on obesity prevalence. As such policies centered around these factors, such as the popular "fast food tax" may lack heft as useful public health instruments.
--------------------
Since, I mentioned methods, I should point out that it was heartening to see such a high level of scientific rigor at these meetings. There was a healthy obsession with causal inference, and nearly all of the papers used fixed effects or instrumental variables. For those who are not into the jargon, fixed effects is best explained by an example: imagine you have data following the same individuals over time. You are interested in learning the effect of some X on Y, but are worried about bias from some omitted variable U, a characteristic about the individual. Fixed effects allow you to essentially subtract of the individual level mean from X and Y. If U doesn't vary across individuals, fixed effects basically washes this confounder out of the estimation procedure. Now you can get at the causal effect X on Y.
Sibling or twin studies are a good example of fixed effects. Let's say you want to learn the causal effects of birthweight on later wages. The worry is that birthweight is correlated with genetic factors or socioeconomic status early in life, which is correlated with outcomes later in adulthood. Using twin fixed effects, you can control for (or difference out) for genes and shared early life socieconomic status.
Of course, if the omitted variables that you worry about change over time for an individual or vary across a set of siblings, fixed effects estimates will not recover causal effects. To get around this researchers often use instrumental variable (IV) methods (either alone or in conjunction with fixed effects), where a factor that affects the regressor of interest, but not the outcome directly or indirectly through some other factor, is used to identify causal impacts. A famous example is the use of the quarter of birth or school cutoff dates to predict attained schooling (individuals born later and near the cutoff date are younger when they finish schooling or a full grade behind when they drop out).
The validity and theoretical basis for instruments are hotly debated, and researchers now must meet a pretty heavy burden of proof to get people interested and convinced. Also, it is now well-known that instruments must predict the regressor of interest strongly enough so as to yield valid estimates: "weak" instruments lead to biases of their own. It was nice to see that researchers at the conference went into great detail when defending their assumptions underlying the use of fixed effects and instruments. It was also nice to see the discussants call these assumptions into question and pointing out the additional implicit assumptions that needed to be made to achieve validity. This sort of discussion forces people to write down an explicit model and all the required identifying assumptions.
At some point though, I couldn't help but feel like there was some overkill and overpolicing, especially with the weak instruments issue (one researcher with a good IV strategy commented that she did not utilize the approach because her instruments were slightly weaker than what is considered kosher). Some new research on IV points suggests the use of estimation techniques that are robust to weak instruments: I was surprised that more conference-goers had not adopted these (indeed, mine was the only paper I saw that used these techniques). Second, some recent research suggests ways to proceed with instruments that might be "slightly" correlated with unobserved factors that influence the outcome and to test the sensitivity of IV results to varying degrees of instrument "badness." I would have liked to have seen a higher rate of adoption of these new techniques.
---------------------------------
In the next installment, I'll speak more about my ASHE experiences by summarizing some research on the early life origins of disease, behavioral economics, and the many benefits of education.
Friday, June 20, 2008
ASHE Conference
I will be attending the American Society for Health Economists (ASHE) Conference this weekend through early next week. Follow the link to check out the conference bill: it looks phenomenal! I will make a concerted attempted to blog about the proceedings in semi-real time, so definitely stay tuned.
Also, I will be presenting and discussing a paper at the conference. The abstract for my paper is provided below (let me know if you are interested in the topic and want to learn more or collaborate). Regarding the latter, I read a long time back in some economist's autobiographical account that being a good discussant and reviewer helps you develop street cred as a researcher. Nothing like a little self-promotion before I disappear from the research world to get plundered by medical school...
Paper Title: The Intergenerational Transmission of Height: Evidence from Mexico
A growing body of work suggests that health may be transferred across generations. This paper has two aims: to quantify intergenerational associations in height, a summary measure of long-run health and nutritional status, and to explore different factors and mechanisms that may generate these correlations. Using data from a rich household survey in Mexico, I use a variety of econometric methods to explore the nature of intergenerational correlations in the heights of parents and their children (aged 0-6 years). In particular, I use conditions faced by mothers and fathers during their childhood years as instruments for their heights, arguing that this strategy focuses attention on the portion of parental height sensitive to environmental conditions and public investment. I also explore gender differences in parent-child associations in height. I find that IV estimates on maternal height are generally twice as large as the corresponding OLS estimates, with the IV coefficient on paternal height near zero. These findings are highly robust to inclusion of a rich set of parental and household characteristics. Furthermore, the association between instrumented maternal height and child height is much larger for boys than for girls across all specifications, which is in contrast to the coefficients on predicted paternal height and measures of household resources. The results suggest that the portion of maternal height sensitive to environmental conditions faced during childhood is an important determinant of child health and, consequently, that early life conditions faced by girls may have intergenerational consequences. More speculatively, the results also suggest biological explanations beyond simple genetic transfers may explain an important portion of mother-child associations in height.
Also, I will be presenting and discussing a paper at the conference. The abstract for my paper is provided below (let me know if you are interested in the topic and want to learn more or collaborate). Regarding the latter, I read a long time back in some economist's autobiographical account that being a good discussant and reviewer helps you develop street cred as a researcher. Nothing like a little self-promotion before I disappear from the research world to get plundered by medical school...
Paper Title: The Intergenerational Transmission of Height: Evidence from Mexico
A growing body of work suggests that health may be transferred across generations. This paper has two aims: to quantify intergenerational associations in height, a summary measure of long-run health and nutritional status, and to explore different factors and mechanisms that may generate these correlations. Using data from a rich household survey in Mexico, I use a variety of econometric methods to explore the nature of intergenerational correlations in the heights of parents and their children (aged 0-6 years). In particular, I use conditions faced by mothers and fathers during their childhood years as instruments for their heights, arguing that this strategy focuses attention on the portion of parental height sensitive to environmental conditions and public investment. I also explore gender differences in parent-child associations in height. I find that IV estimates on maternal height are generally twice as large as the corresponding OLS estimates, with the IV coefficient on paternal height near zero. These findings are highly robust to inclusion of a rich set of parental and household characteristics. Furthermore, the association between instrumented maternal height and child height is much larger for boys than for girls across all specifications, which is in contrast to the coefficients on predicted paternal height and measures of household resources. The results suggest that the portion of maternal height sensitive to environmental conditions faced during childhood is an important determinant of child health and, consequently, that early life conditions faced by girls may have intergenerational consequences. More speculatively, the results also suggest biological explanations beyond simple genetic transfers may explain an important portion of mother-child associations in height.
Monday, June 16, 2008
The P-Value Contest
Many of you have likely come across one of the following sentences while perusing empirical work (doesn't matter what discipline or field):
"...the effect was statistically significant (p = 0.0401)..."
"...as per convention, we define statistical significance as a p-value of 0.05..."
"...income was significant at standard levels of confidence (p = 0.049)..."
0.05, or 5%, is the magic p-value (loosely, the probability that the given estimate or test statistic is due to random chance) that denotes the threshold separating statistical significance from insignificance. You don't need to be a Bayesian to realize that this designation is completely arbitrary: why not 0.04 (4%) or 0.06 (6%)?
I spent some time today (read: procrastinating) trying to find the story behind the origin of this convention. The most I could find was that R.A. Fischer, the founding father of statistics, decreed this as an "acceptable value" and everyone started to copy it.
I'm not satisfied: I'm guessing there is a fascinating story here. Why did Fischer choose 0.05 in the first place? How did the convention spread? Was it ever challenged? How do conventions develop in general?
This brings us to this summer's contest: whoever finds the best story (link/paper/book) behind the 5% convention will receive a copy of a recent popular press economics book of their choice. The prize is a small price for me to pay to have someone else do the work and bring the story to me - everyone wins.
"...the effect was statistically significant (p = 0.0401)..."
"...as per convention, we define statistical significance as a p-value of 0.05..."
"...income was significant at standard levels of confidence (p = 0.049)..."
0.05, or 5%, is the magic p-value (loosely, the probability that the given estimate or test statistic is due to random chance) that denotes the threshold separating statistical significance from insignificance. You don't need to be a Bayesian to realize that this designation is completely arbitrary: why not 0.04 (4%) or 0.06 (6%)?
I spent some time today (read: procrastinating) trying to find the story behind the origin of this convention. The most I could find was that R.A. Fischer, the founding father of statistics, decreed this as an "acceptable value" and everyone started to copy it.
I'm not satisfied: I'm guessing there is a fascinating story here. Why did Fischer choose 0.05 in the first place? How did the convention spread? Was it ever challenged? How do conventions develop in general?
This brings us to this summer's contest: whoever finds the best story (link/paper/book) behind the 5% convention will receive a copy of a recent popular press economics book of their choice. The prize is a small price for me to pay to have someone else do the work and bring the story to me - everyone wins.
Friday, June 13, 2008
Randomized Experiments
Great piece in this week's Economist about the increasing use of randomized experiments in the field of development economics and the methodology's potential usefulness in informing policy. (Here is an earlier post in this space on the same topic.)
I did have one minor issue with the following passage:
Go back to the bednets once more. You might conclude that the trial showed that they should always be given away. Yet it turns out that millions of nets were already in use in the part of Kenya where the field trial took place, so their value was known. The experiment guaranteed supplies, so it did not test the assertion that you need to charge something to encourage reliable suppliers. And the recipients were pregnant women, whereas the point of giving bednets away is to provide anti-malaria treatment universally. The evidence from western Kenya was clear. But it hardly settled the question of whether the government should give bednets away across the country. Questions like that may still have to be made on the basis of the soft evidence that randomistas turn up their noses at.
In my eyes, this point really gets at the value of replication. An well designed experiment carried out at a single point in time and space offers a way to get around statistical bias. However, the generalizability of such results is never clear. Reasoned projection to other contexts is one way to apply the results of one experiment to another context. However, I would think the ideal way to get at this would be, if possible, to replicate the experiment in different regions and time-points. This is has been long recognized in the medical world: everyone seems to realize that you can't rely on a single drug trial on a group of middle-aged males to project treatment effects across age and gender (though actual practice has not quite caught up to this belief).
Replication is likely undervalued among researchers and the money-men alike. Re-doing someone's experiment won't get you published in the American Economic Review (unless you find the opposite result or something) and once a large experiment for one purpose has been funded, I can see the loss of interest among donors to do it again. Hopefully, this incentive structure changes so that we can derive true context-specific treatment effects that, combined with reasoned projections (we do want to stop conducting the same study whence reasonable), can give us a better sense of policy directions, as opposed to projecting wildly based on single studies alone.
I did have one minor issue with the following passage:
Go back to the bednets once more. You might conclude that the trial showed that they should always be given away. Yet it turns out that millions of nets were already in use in the part of Kenya where the field trial took place, so their value was known. The experiment guaranteed supplies, so it did not test the assertion that you need to charge something to encourage reliable suppliers. And the recipients were pregnant women, whereas the point of giving bednets away is to provide anti-malaria treatment universally. The evidence from western Kenya was clear. But it hardly settled the question of whether the government should give bednets away across the country. Questions like that may still have to be made on the basis of the soft evidence that randomistas turn up their noses at.
In my eyes, this point really gets at the value of replication. An well designed experiment carried out at a single point in time and space offers a way to get around statistical bias. However, the generalizability of such results is never clear. Reasoned projection to other contexts is one way to apply the results of one experiment to another context. However, I would think the ideal way to get at this would be, if possible, to replicate the experiment in different regions and time-points. This is has been long recognized in the medical world: everyone seems to realize that you can't rely on a single drug trial on a group of middle-aged males to project treatment effects across age and gender (though actual practice has not quite caught up to this belief).
Replication is likely undervalued among researchers and the money-men alike. Re-doing someone's experiment won't get you published in the American Economic Review (unless you find the opposite result or something) and once a large experiment for one purpose has been funded, I can see the loss of interest among donors to do it again. Hopefully, this incentive structure changes so that we can derive true context-specific treatment effects that, combined with reasoned projections (we do want to stop conducting the same study whence reasonable), can give us a better sense of policy directions, as opposed to projecting wildly based on single studies alone.
Thursday, June 12, 2008
Public Health Priorities
Chris Blattman has an interesting post about the campaign to address the AIDS crisis. Some observers believe that the prevalence of AIDS has been completely overblown and that public health dollars are being allocated to this cause without due cause from the "hard evidence." A more detailed discussion is available in last week's Economist. The key phrase from that piece:
"...because of the single issue-activism that AIDS inspires, it receives a quarter of global health aid even though it causes only 5% of the burden of disease in poor and middle income countries. [Observers] also claim that ear-marking money in this way makes it harder to strengthen the health systems of those countries."
A very similar argument can be (and has been) advanced against organizations like Partners for Health.
So why are public health issues dominated by certain issues and not others? There are likely several reasons. First, it's likely easier for the public to identify with a single cause or disease and, therefore, it is easier to raise money targeting that particular condition. Second, diseases in general appear to be sexier than more diffuse problems. For example, one could argue that hunger is the proximal cause of most death and disease in the developing world. Somehow, AIDS, Malaria and diseases that lend themselves to the horrors of the imagination and the (potential) wonders of science are more eye-catching and press-worthy than concepts such as caloric intake and exposure to indoor air pollution (the latter thought to be the second leading cause of death and disease among children in the developing world).
Indeed, I think a lot of the dynamics in attention paid to given public health issues and policy and spending priorities might be explained by theories from political science (Kingdon's issue attention cycle is an example). Does anyone out there know of good work on this subject? I'm sure there is something out there...
Finally, are there ways to take advantage of spillovers from a great deal of attention towards a single disease or issue? It seems natural to me that attention for AIDS among the poor should increase attention to the myriad of other problems facing these societies as well; this simply seems like a matter of advertising to me. Furthermore, I don't see why this couldn't extend to the financial side: if grants to countries are made fungible (within certain bounds and fairly stringent monitoring of usage), there is no reason why AIDS money can't be nutrition money. I'd definitely appreciate your thoughts on these issues.
"...because of the single issue-activism that AIDS inspires, it receives a quarter of global health aid even though it causes only 5% of the burden of disease in poor and middle income countries. [Observers] also claim that ear-marking money in this way makes it harder to strengthen the health systems of those countries."
A very similar argument can be (and has been) advanced against organizations like Partners for Health.
So why are public health issues dominated by certain issues and not others? There are likely several reasons. First, it's likely easier for the public to identify with a single cause or disease and, therefore, it is easier to raise money targeting that particular condition. Second, diseases in general appear to be sexier than more diffuse problems. For example, one could argue that hunger is the proximal cause of most death and disease in the developing world. Somehow, AIDS, Malaria and diseases that lend themselves to the horrors of the imagination and the (potential) wonders of science are more eye-catching and press-worthy than concepts such as caloric intake and exposure to indoor air pollution (the latter thought to be the second leading cause of death and disease among children in the developing world).
Indeed, I think a lot of the dynamics in attention paid to given public health issues and policy and spending priorities might be explained by theories from political science (Kingdon's issue attention cycle is an example). Does anyone out there know of good work on this subject? I'm sure there is something out there...
Finally, are there ways to take advantage of spillovers from a great deal of attention towards a single disease or issue? It seems natural to me that attention for AIDS among the poor should increase attention to the myriad of other problems facing these societies as well; this simply seems like a matter of advertising to me. Furthermore, I don't see why this couldn't extend to the financial side: if grants to countries are made fungible (within certain bounds and fairly stringent monitoring of usage), there is no reason why AIDS money can't be nutrition money. I'd definitely appreciate your thoughts on these issues.
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