Spring time in Upstate New York means high school tennis. My former team, the Shenendehowa Plainsmen, are once again in the running to win the Section II Class A title. I think we've won like 7 of these since I graduated in 1998, following a very long dry spell (which should tell you something about how much I contributed to our school's success!).
Anyway, today's Albany Times Union has a great article about Shen's starting third doubles player who, due to several congenital anomalies, plays and wins without most of his fingers, toes, and the ability to see out of his right eye. A really great story.
Also, the article quotes Gene Gould, Shen's longtime coach. It's great to see him still at the helm, coaching so many championship level teams.
Sunday, May 18, 2008
Monday, May 12, 2008
Hepatitis B and Pro-Male Sex Ratios Revisited
Many of you are probably aware of Emily Oster's controversial study on the potential (causal) effects of Hepatitis B on population gender ratios (see here for a non-technical summary). Oster's paper sparked a great debate as to whether the disease could truly explain a significant portion of the gender imbalance in many of the Asian countries, such as China, where the male/female ratios are remarkably large. Oster and Gang Chen recently revisited the Hepatitis B hypothesis as it applies to China. Their findings:
Earlier work (Oster, 2005) has argued, based on existing medical literature and analysis of cross country data and vaccination programs, that parents who are carriers of hepatitis B have a higher offspring sex ratio (more boys) than non-carrier parents. Further, since a number of Asian countries, China in particular, have high hepatitis B carrier rates, Oster (2005) suggested that hepatitis B could explain a large share - approximately 50% - of Asia's \missing women". Subsequent work has questioned this conclusion. Most notably, Lin and Luoh (2008) use data from a large cohort of births in Taiwan and find only a very tiny effect of maternal hepatitis carrier status on offspring sex ratio. Although this work is quite conclusive for the case of mothers, it leaves open the possibility that paternal carrier status is driving higher sex offspring sex ratios. To test this, we collected data on the offspring gender for a cohort of 67,000 people in China who are being observed in a prospective cohort study of liver cancer; approximately 15% of these individuals are hepatitis B carriers. In this sample, we find no effect of either maternal or paternal hepatitis B carrier status on offspring sex. Carrier parents are no more likely to have male children than non-carrier parents. This finding leads us to conclude that hepatitis B cannot explain skewed sex ratios in China.
For what it's worth, I applaud Oster, who is clearly a top-flight researcher doing interesting work, for her academic courage and honesty. It's just great to see an example where one's ego does not interfere with his/her quest to learn the Truth. Good lesson for graduate students such as myself.
Furthermore, despite this retraction (at least with respect to China), Oster is not leaving the topic behind. Indeed, the fact that Hepatitis B explains a good deal of the gender imbalance in some countries but not others is intriguing and worthy of further exploration. This is exactly what she is doing this new working paper, which attempts to reconcile the scientific and population evidence on Hep B and sex ratios.
Excellent research on an interesting line of work. I'd be curious to see how this plays out in the future.
[Ed - 5/13/08 - I was recently informed that the Marginal Revolution blog put up a very similar post yesterday on this topic. Just for the record, I wrote this post as soon as I saw Oster's NBER working paper, and prior to me finding out what other blogs had to say. Also, just as an FYI, you might want to check out the comments under said MR post. The discussion there is pretty interesting.]
Earlier work (Oster, 2005) has argued, based on existing medical literature and analysis of cross country data and vaccination programs, that parents who are carriers of hepatitis B have a higher offspring sex ratio (more boys) than non-carrier parents. Further, since a number of Asian countries, China in particular, have high hepatitis B carrier rates, Oster (2005) suggested that hepatitis B could explain a large share - approximately 50% - of Asia's \missing women". Subsequent work has questioned this conclusion. Most notably, Lin and Luoh (2008) use data from a large cohort of births in Taiwan and find only a very tiny effect of maternal hepatitis carrier status on offspring sex ratio. Although this work is quite conclusive for the case of mothers, it leaves open the possibility that paternal carrier status is driving higher sex offspring sex ratios. To test this, we collected data on the offspring gender for a cohort of 67,000 people in China who are being observed in a prospective cohort study of liver cancer; approximately 15% of these individuals are hepatitis B carriers. In this sample, we find no effect of either maternal or paternal hepatitis B carrier status on offspring sex. Carrier parents are no more likely to have male children than non-carrier parents. This finding leads us to conclude that hepatitis B cannot explain skewed sex ratios in China.
For what it's worth, I applaud Oster, who is clearly a top-flight researcher doing interesting work, for her academic courage and honesty. It's just great to see an example where one's ego does not interfere with his/her quest to learn the Truth. Good lesson for graduate students such as myself.
Furthermore, despite this retraction (at least with respect to China), Oster is not leaving the topic behind. Indeed, the fact that Hepatitis B explains a good deal of the gender imbalance in some countries but not others is intriguing and worthy of further exploration. This is exactly what she is doing this new working paper, which attempts to reconcile the scientific and population evidence on Hep B and sex ratios.
Excellent research on an interesting line of work. I'd be curious to see how this plays out in the future.
[Ed - 5/13/08 - I was recently informed that the Marginal Revolution blog put up a very similar post yesterday on this topic. Just for the record, I wrote this post as soon as I saw Oster's NBER working paper, and prior to me finding out what other blogs had to say. Also, just as an FYI, you might want to check out the comments under said MR post. The discussion there is pretty interesting.]
Sunday, May 11, 2008
Bad Timing
My doorbell rang last Friday around 9 PM. I happened to be home and, figuring it was my roommate or some other tenant having forgotten their key to get inside, I decided to head downstairs and answer.
To my surprise, I was greeted by two well-dressed white males in their 20s, one of whom as carrying a clip-board. They explained that they were representing a state-wide environmental lobby and went on to talk about a bill they were trying to get passed and how they needed my $15 dollars to do it.
I normally don't provide money to solicitors who accost me in person or over the phone, so the chances that these two would ever get anything from me was pretty low to begin with. However, in this instance, the probability that I would part with my money was pretty much zero given the bizarre timing of their request.
Who comes to your door on Friday night to collect money for the environment? Hardly anyone, I would think. First off, most people are either not around on Friday or want to enjoy the start of their weekends by winding down with family, friends or with a good movie or book. So to have someone at your door at that time is a bit unexpected and, as such, a little scary. Indeed, at one point I thought these guys were going to overpower me and then clean out my apartment.
Not only that, I wasn't sure how this strategy was a good idea from their standpoint, either. For a solicitor, I'd bet the returns to going around on a Friday night are quite low since people will either not be around or too shocked/annoyed to want to listen to any kind of pitch.
So I asked the two solicitors: "This is a bit strange. Why are you guys doing this on Friday night?"
Their answer: "The environment never rests."
They still didn't get any money from me.
To my surprise, I was greeted by two well-dressed white males in their 20s, one of whom as carrying a clip-board. They explained that they were representing a state-wide environmental lobby and went on to talk about a bill they were trying to get passed and how they needed my $15 dollars to do it.
I normally don't provide money to solicitors who accost me in person or over the phone, so the chances that these two would ever get anything from me was pretty low to begin with. However, in this instance, the probability that I would part with my money was pretty much zero given the bizarre timing of their request.
Who comes to your door on Friday night to collect money for the environment? Hardly anyone, I would think. First off, most people are either not around on Friday or want to enjoy the start of their weekends by winding down with family, friends or with a good movie or book. So to have someone at your door at that time is a bit unexpected and, as such, a little scary. Indeed, at one point I thought these guys were going to overpower me and then clean out my apartment.
Not only that, I wasn't sure how this strategy was a good idea from their standpoint, either. For a solicitor, I'd bet the returns to going around on a Friday night are quite low since people will either not be around or too shocked/annoyed to want to listen to any kind of pitch.
So I asked the two solicitors: "This is a bit strange. Why are you guys doing this on Friday night?"
Their answer: "The environment never rests."
They still didn't get any money from me.
Tuesday, May 6, 2008
Fetal Origins Plus
I've spent some time on this blog talking about the influence of fetal and early childhood events on later health and economic outcomes (see, for example, here). Recently, I was scouring the web for some of the medical literature on this subject, and came across this great website. The site summarizes the seminal body of work conducted by David Barker and colleagues on the fetal origins hypothesis, providing non-technical summaries of a variety of research strands and key citations to the most important papers written on the subject. Definitely check it out.
As I mentioned in the linked post above, the fetal programming literature has gained great currency among economists. However, little work has been done on fetal origins in the context of other investments and events and individual receives or faces in the course of his or her life cycle. James Heckman's recent paper in the Proceedings of the National Academy of Sciences synthesizes these literatures, linking health, cognition and other skills in the process (you can find a more general statement of Heckman's research agenda here). It's a great read that highlights the fact that there is a great deal of research required to fully understand and characterize many aspects of human capital accumulation. (Self-promotion: this is good news for me, as much of my dissertation deals with these topics.)
As I mentioned in the linked post above, the fetal programming literature has gained great currency among economists. However, little work has been done on fetal origins in the context of other investments and events and individual receives or faces in the course of his or her life cycle. James Heckman's recent paper in the Proceedings of the National Academy of Sciences synthesizes these literatures, linking health, cognition and other skills in the process (you can find a more general statement of Heckman's research agenda here). It's a great read that highlights the fact that there is a great deal of research required to fully understand and characterize many aspects of human capital accumulation. (Self-promotion: this is good news for me, as much of my dissertation deals with these topics.)
Saturday, May 3, 2008
A Prospectus for the Rest of Us!
In a few weeks, I will have officially completed my third year as a PhD student (or my fifth year of my MD/PhD quest, which sounds a lot sadder). Part and parcel with this achievement comes a fairly major institutional requirement: I have to submit my 20 page research prospectus by mid June. Completion of the prospectus promotes me to "candidacy." (I only recently realized the significance of this term. My e-mail footer for the last three years had ended with "PhD Candidate." Apparently, by doing so, I've "lied to thousands of people" since coming to Yale).
Like most things I do, I've approached the whole prospectus writing process in a seriously manic, yet somehow careless, fashion. The way this is supposed to work is that you first come up with a question, then talk to your committee (or those who you intend to con into being on your committee), then write the prospectus based on those ideas, and then carry out the research. My process has been almost opposite: do the research, form the committee, get confused between several ideas, talk to the committee, toss around two more large ideas, and, ultimately, set off on writing the prospectus. In some sense, I've treated the prospectus as something that comes into place once I've generated enough data. The problem with doing this is that your ideas might be so disparate that they do not naturally fit together into a thematic dissertation (though you can make the theme as vague as you want, perhaps, to get around this) or you explore so many things that you are confused between different directions you could pursue. This is my problem now. I am fairly confident about two of my papers, but the lead paper - well, that remains something to be decided!
That being said, for the purposes of the prospectus, none of this actually matters! The point is to have something coherent down that the graduate committee thinks is interesting, doable and illustrative of your knowledge of the field. Not everything you write in the prospectus has to work out. Given this, perhaps the best thing to do is to find something you are broadly interested in, figure out some specific questions and data sources you could use, get the prospectus done early and then go to town. This is what I would advocate to other grad students in the pipeline and I am certainly in position to do this right now.
But, for whatever reason, I don't want to submit my prospectus until I am confident that all three papers I propose will materialize in the final dissertation. Given what I just said, this is irrational: I think this is a pretty good example of cognitive dissonance or, more precisely, some kind of pre-emptive action to avoid cognitive dissonance. I don't want to hand in something other than what I said I would hand in - I don't want to appear inconsistent over time.
Well, it's time to bite the bullet. I am currently working on finishing up this prospectus. I plan on studying the astonishingly quick transition of low and middle income countries from malnutrition to obesity, particularly focusing on the intersection between biology and economic factors that may drive such changes (paper 1), as well as intergenerational transfers of health status. (papers 2 and 3).
Hopefully, whatever I produce and hand in will follow this script. And if it doesn't...well, I guess thats OK, too.
Like most things I do, I've approached the whole prospectus writing process in a seriously manic, yet somehow careless, fashion. The way this is supposed to work is that you first come up with a question, then talk to your committee (or those who you intend to con into being on your committee), then write the prospectus based on those ideas, and then carry out the research. My process has been almost opposite: do the research, form the committee, get confused between several ideas, talk to the committee, toss around two more large ideas, and, ultimately, set off on writing the prospectus. In some sense, I've treated the prospectus as something that comes into place once I've generated enough data. The problem with doing this is that your ideas might be so disparate that they do not naturally fit together into a thematic dissertation (though you can make the theme as vague as you want, perhaps, to get around this) or you explore so many things that you are confused between different directions you could pursue. This is my problem now. I am fairly confident about two of my papers, but the lead paper - well, that remains something to be decided!
That being said, for the purposes of the prospectus, none of this actually matters! The point is to have something coherent down that the graduate committee thinks is interesting, doable and illustrative of your knowledge of the field. Not everything you write in the prospectus has to work out. Given this, perhaps the best thing to do is to find something you are broadly interested in, figure out some specific questions and data sources you could use, get the prospectus done early and then go to town. This is what I would advocate to other grad students in the pipeline and I am certainly in position to do this right now.
But, for whatever reason, I don't want to submit my prospectus until I am confident that all three papers I propose will materialize in the final dissertation. Given what I just said, this is irrational: I think this is a pretty good example of cognitive dissonance or, more precisely, some kind of pre-emptive action to avoid cognitive dissonance. I don't want to hand in something other than what I said I would hand in - I don't want to appear inconsistent over time.
Well, it's time to bite the bullet. I am currently working on finishing up this prospectus. I plan on studying the astonishingly quick transition of low and middle income countries from malnutrition to obesity, particularly focusing on the intersection between biology and economic factors that may drive such changes (paper 1), as well as intergenerational transfers of health status. (papers 2 and 3).
Hopefully, whatever I produce and hand in will follow this script. And if it doesn't...well, I guess thats OK, too.
Sunday, April 27, 2008
Cheerleaders in India
My parents recently got a DirecTV package covering the entire Indian Premier League (IPL) cricket season. I am home this weekend and have spent my mornings watching some of the matches and I have to say that these games are fantastic! The teams, comprised of the cream-of-the-crop of world cricket, play to capacity crowds and provide an intensity that matches some of the best international contests.
An interesting feature of the IPL is the presence of cheerleaders. During the opening weekend of league play, the Washington Redskin cheerleaders did a dance number for shocked/delighted Indian crowds. Following their lead, each team has its own set of cheerleaders, who dance around the boundaries in the same fashion as NFL cheerleaders do on the sidelines.
In Saturday's matches, I was surprised to note that the cheerleaders wore extremely revealing outfits. The exception were the Chennai Super King girls who, reflecting the still traditional ethos of the city, were fully clothed. However, during today's matches, cheerleaders for the Mumbai Indians covered their midriffs and legs and those for the opposing Deccan Chargers went a step further and wore reasonably demure Indian-style outfits.
Why the change? Apparently, the cheerleaders have caused quite a stir among conservatives in India, who find the whole concept "vulgar."
I find the whole hullabaloo to be ridiculous. Here's why:
1) I think Indians have a skewed concept of vulgarity. How are cheerleaders in short skirts more vulgar than the content of a typical Hindi movie, with all the gyrating and suggestive imagery/lyrics? It's pretty hypocritical for high level ministers to run around and comment on cheerleading when the very elements the criticize are present in their own region's media.
2) In the link posted above, one of the cheerleaders comments:
"We do expect people to pass lewd, snide remarks but I am shocked by the nature and magnitude of the comments people pass here (in India)" cheerleader Tabitha from Uzbekistan said.
An interesting feature of the IPL is the presence of cheerleaders. During the opening weekend of league play, the Washington Redskin cheerleaders did a dance number for shocked/delighted Indian crowds. Following their lead, each team has its own set of cheerleaders, who dance around the boundaries in the same fashion as NFL cheerleaders do on the sidelines.
In Saturday's matches, I was surprised to note that the cheerleaders wore extremely revealing outfits. The exception were the Chennai Super King girls who, reflecting the still traditional ethos of the city, were fully clothed. However, during today's matches, cheerleaders for the Mumbai Indians covered their midriffs and legs and those for the opposing Deccan Chargers went a step further and wore reasonably demure Indian-style outfits.
Why the change? Apparently, the cheerleaders have caused quite a stir among conservatives in India, who find the whole concept "vulgar."
I find the whole hullabaloo to be ridiculous. Here's why:
1) I think Indians have a skewed concept of vulgarity. How are cheerleaders in short skirts more vulgar than the content of a typical Hindi movie, with all the gyrating and suggestive imagery/lyrics? It's pretty hypocritical for high level ministers to run around and comment on cheerleading when the very elements the criticize are present in their own region's media.
2) In the link posted above, one of the cheerleaders comments:
"We do expect people to pass lewd, snide remarks but I am shocked by the nature and magnitude of the comments people pass here (in India)" cheerleader Tabitha from Uzbekistan said.
"Be it a 70-year-old or a 15-year-old kid they all letch at us and make amorous advances.
"We are living in constant fear of being molested," she bemoaned.
Sadly, this is an experience shared by many women I know (especially foreigners) who have either traveled through or lived in India for some period of time. My running theory is that this can be chalked up to repression. Short of a large scale cultural education in how to treat women (which is definitely needed in many parts of the world), perhaps the very presence of cheerleaders can go so distance in lowering the "shock value" of sexuality in India, thus helping quell the kinds of wolfish behaviors that happen in regimes of repression.Monday, April 21, 2008
Soccer and the "Culture of Violence"
Check out this recent paper by Ted Miguel and coauthors using soccer match infractions as a lens to explore the link between culture and violence. Here is the abstract:
Can some acts of violence be explained by a society's "culture"? Scholars have found it hard to empirically disentangle the effects of culture, legal institutions, and poverty in driving violence. We address this problem by exploiting a natural experiment offered by the presence of thousands of international soccer (football) players in the European professional leagues. We find a strong relationship between the history of civil conflict in a player's home country and his propensity to behave violently on the soccer field, as measured by yellow and red cards. This link is robust to region fixed effects, country characteristics (e.g., rule of law, per capita income), player characteristics (e.g., age, field position, quality), outliers, and team fixed effects. Reinforcing our claim that we isolate cultures of violence rather than simple rule-breaking or something else entirely, there is no meaningful correlation between a player's home country civil war history and soccer performance measures not closely related to violent conduct.
Can some acts of violence be explained by a society's "culture"? Scholars have found it hard to empirically disentangle the effects of culture, legal institutions, and poverty in driving violence. We address this problem by exploiting a natural experiment offered by the presence of thousands of international soccer (football) players in the European professional leagues. We find a strong relationship between the history of civil conflict in a player's home country and his propensity to behave violently on the soccer field, as measured by yellow and red cards. This link is robust to region fixed effects, country characteristics (e.g., rule of law, per capita income), player characteristics (e.g., age, field position, quality), outliers, and team fixed effects. Reinforcing our claim that we isolate cultures of violence rather than simple rule-breaking or something else entirely, there is no meaningful correlation between a player's home country civil war history and soccer performance measures not closely related to violent conduct.
Saturday, April 19, 2008
Why Your Congressman's Children Matter to You
Understanding how legislators, and government officials more broadly, form opinions and make decisions is crucial for understanding the broader political climate and predicting policy change. A recent paper in the American Economic Review by Yale economist and political scientist Ebonya Washington addresses this issue with an interesting angle and some startling results:
Parenting daughters, sociologists have shown, increases feminist sympathies. I test the hypothesis that children, much like neighbors or peers, can influence parental behavior. I demonstrate that conditional on total number of children, each daughter increases a congressperson's propensity to vote liberally, particularly on reproductive rights issues. The results identify an important (and previously omitted) explanatory variable in the literature on congressional decision making. Additionally the paper highlights the relevance of child-to-parent behavioral influence.
The crucial assumption in this paper is that the sex composition of the legislator's children is random or, at the very least, unrelated to other factors that might determine voting behavior. Washington addresses this by noting that 1) the time period covered in the study predated the wide-spread diffusion of fetal sex-determining technologies and 2) legislator's do not appear to follow different stopping rules conditional on the sex of birth's children. To address (2) the author utilizes information on the sex of the legislator's first birth (painstakingly recovered from newspaper announcements) and assess whether the total number of children varies with the first kid's gender (she finds that it does not).
A recent working paper by Dalton Conley and Brian McCabe utilizes Washington's finding to study the link between legislator voting behavior and campaign contributions. Noting that recovering causal estimates of this relationship is difficult, the authors use the sex composition of children to predict voting behavior, and then assess the relationship between predicted voting behavior and campaign contributions. The key assumption is that the gender mix of the kids doesn't have a direct, or indirect (via some unobserved factor), influence on campaign contributions.
Parenting daughters, sociologists have shown, increases feminist sympathies. I test the hypothesis that children, much like neighbors or peers, can influence parental behavior. I demonstrate that conditional on total number of children, each daughter increases a congressperson's propensity to vote liberally, particularly on reproductive rights issues. The results identify an important (and previously omitted) explanatory variable in the literature on congressional decision making. Additionally the paper highlights the relevance of child-to-parent behavioral influence.
The crucial assumption in this paper is that the sex composition of the legislator's children is random or, at the very least, unrelated to other factors that might determine voting behavior. Washington addresses this by noting that 1) the time period covered in the study predated the wide-spread diffusion of fetal sex-determining technologies and 2) legislator's do not appear to follow different stopping rules conditional on the sex of birth's children. To address (2) the author utilizes information on the sex of the legislator's first birth (painstakingly recovered from newspaper announcements) and assess whether the total number of children varies with the first kid's gender (she finds that it does not).
A recent working paper by Dalton Conley and Brian McCabe utilizes Washington's finding to study the link between legislator voting behavior and campaign contributions. Noting that recovering causal estimates of this relationship is difficult, the authors use the sex composition of children to predict voting behavior, and then assess the relationship between predicted voting behavior and campaign contributions. The key assumption is that the gender mix of the kids doesn't have a direct, or indirect (via some unobserved factor), influence on campaign contributions.
Sunday, April 13, 2008
Sex Selection Shocker
Amartya Sen wrote his famous piece on systematic gender bias, provocatively titled "More Than 100 Million Women are Missing," nearly 18 years ago. Since then, a great deal of work has looked at the causes of the pro-male sex ratio seen in many parts of the world, particularly Asia. Even so, it is a phenomenon we do not understand well and the problem has certainly not gone away. Indeed, two of the largest offenders, India (the North mainly) and China, appear to be going strong with these practices, likely driven by the diffusion of technology allowing prenatal sex determination.
Despite widespread prevalence of pro-male sex ratios, and being brought to attention about these sad demographic curiosities nearly two decades ago, I always seemed to be shocked by the latest statistic on gender bias. A recent paper by Douglas Almond and Lena Edlund, published in the Proceedings of the National Academy of Sciences, literally made me fall out of my chair. Here's the punchline:
We document male-biased sex ratios among U.S.-born children of Chinese, Korean, and Asian Indian parents in the 2000 U.S. Census. This male bias is particularly evident for third children: If there was no previous son, sons outnumbered daughters by 50%. By contrast, the sex ratios of eldest and younger children with an older brother were both within the range of the biologically normal, as were White offspring sex ratios (irrespective of the elder siblings' sex). We interpret the found deviation in favor of sons to be evidence of sex selection, most likely at the prenatal stage.
Of course, nobody should be surprised that this involves Asian parents. But this is happening in the United States and the data comes from the 2000 Census. Wow. I truly hope Almond and Edlund are working on a follow up to characterize what exactly is going on here: obviously abortion is a hush-hush topic, but it is hard for me to imagine Asian parents in the United States (whatever flavor) deliberately getting one in order to avoid a having a girl.
Also, I wonder if this bias is apparent among live births, as well. That is, within families, to parents (especially the Asian kind) systematically favor boys over girls? I am not sure a U.S. sample survey with large enough numbers of Asian families and child-by-child measures of parental investments is available (perhaps the CPS?) for analysis. But I would be interested to see some results if there is data out there.
Finally, gender bias is not restricted to Asian families. An intriguing paper by Enrico Moretti and Gordon Dahl finds the following results for the United States:
This paper shows how parental preferences for sons versus daughters affect divorce, child custody, marriage, shotgun marriage when the sex of the child is known before birth, and fertility stopping rules. We document that parents with girls are significantly more likely to be divorced, that divorced fathers are more likely to have custody of their sons, and that women with only girls are substantially more likely to have never been married. Perhaps the most striking evidence comes from the analysis of shotgun marriages. Among those who have an ultrasound test during their pregnancy, mothers carrying a boy are more likely to be married at delivery. When we turn to fertility, we find that in families with at least two children, the probability of having another child is higher for all-girl families than all-boy families. This preference for sons seems to be largely driven by fathers, with men reporting they would rather have a boy by more than a two to one margin. In the final part of the paper, we compare the effects for the U.S. to five developing countries.
Despite widespread prevalence of pro-male sex ratios, and being brought to attention about these sad demographic curiosities nearly two decades ago, I always seemed to be shocked by the latest statistic on gender bias. A recent paper by Douglas Almond and Lena Edlund, published in the Proceedings of the National Academy of Sciences, literally made me fall out of my chair. Here's the punchline:
We document male-biased sex ratios among U.S.-born children of Chinese, Korean, and Asian Indian parents in the 2000 U.S. Census. This male bias is particularly evident for third children: If there was no previous son, sons outnumbered daughters by 50%. By contrast, the sex ratios of eldest and younger children with an older brother were both within the range of the biologically normal, as were White offspring sex ratios (irrespective of the elder siblings' sex). We interpret the found deviation in favor of sons to be evidence of sex selection, most likely at the prenatal stage.
Of course, nobody should be surprised that this involves Asian parents. But this is happening in the United States and the data comes from the 2000 Census. Wow. I truly hope Almond and Edlund are working on a follow up to characterize what exactly is going on here: obviously abortion is a hush-hush topic, but it is hard for me to imagine Asian parents in the United States (whatever flavor) deliberately getting one in order to avoid a having a girl.
Also, I wonder if this bias is apparent among live births, as well. That is, within families, to parents (especially the Asian kind) systematically favor boys over girls? I am not sure a U.S. sample survey with large enough numbers of Asian families and child-by-child measures of parental investments is available (perhaps the CPS?) for analysis. But I would be interested to see some results if there is data out there.
Finally, gender bias is not restricted to Asian families. An intriguing paper by Enrico Moretti and Gordon Dahl finds the following results for the United States:
This paper shows how parental preferences for sons versus daughters affect divorce, child custody, marriage, shotgun marriage when the sex of the child is known before birth, and fertility stopping rules. We document that parents with girls are significantly more likely to be divorced, that divorced fathers are more likely to have custody of their sons, and that women with only girls are substantially more likely to have never been married. Perhaps the most striking evidence comes from the analysis of shotgun marriages. Among those who have an ultrasound test during their pregnancy, mothers carrying a boy are more likely to be married at delivery. When we turn to fertility, we find that in families with at least two children, the probability of having another child is higher for all-girl families than all-boy families. This preference for sons seems to be largely driven by fathers, with men reporting they would rather have a boy by more than a two to one margin. In the final part of the paper, we compare the effects for the U.S. to five developing countries.
Tuesday, April 8, 2008
Experiments and Corruption
A recurrent theme of this blog has been how clever empirical analysis can be used to recover causal effects in observational data. Such statistical tools are important because, in many cases, individuals or regions cannot be randomly assigned to various states that we are interested. At the same time, however, the use of field experiments, both to assess causal effects and to test various theories, is becoming more prevalent in economics, political science and public health. In an earlier post, I talked about the Jameel Poverty Action Lab, a group set up by economists primarily based at MIT and Harvard which uses experiments to test out different local development interventions.
Another benefit of the experimental method is that it allows one to quantify things that are very hard to measure in even the most detailed surveys. This doesn't just include behavioral concepts such as individual preferences, risk aversion, or discount rates, but also phenomenon like corruption, where survey respondents may be loath to reveal their true history of actions due to fears of legal ramification.
Experiments looking at corruption are slowly growing in number. Just recently, I read a paper (no links available) by two Yale political science graduate students looking at the effects of the Indian Right to Information act versus corrupt practices versus the by-the-books apply and wait method in helping slum dwellers in New Delhi receive government ration cards, which serves as a form of ID as well as a means for accessing fair price food shops. In order to get a ration card, individuals have to fill out an application and prove that they meet a particular means test (i.e., their income must be below some threshold). The authors found that nothing greased the wheels quite like corruption, but the Right to Information request did allow individuals to get their ration cards reasonably quickly. Not a single member of the control group, who merely filled out an application for the car, received a ration card even some 7 months after the experiment began.
This experiment is similar in spirit to one recently published in the Quarterly Journal of Economics, which considers the influence of corruption in obtaining a driver's license in India. From the abstract:
We study the allocation of driver's licenses in India by randomly assigning applicants to one of three groups: bonus (offered a bonus for obtaining a license quickly), lesson (offered free driving lessons), or comparison. Both the bonus and lesson groups are more likely to obtain licenses. However, bonus group members are more likely to make extralegal payments and to obtain licenses without knowing how to drive. All extralegal payments happen through private intermediaries ("agents"). An audit study of agents reveals that they can circumvent procedures such as the driving test. Overall, our results support the view that corruption does not merely reflect transfers from citizens to bureaucrats but distorts allocation.
Some self-promotion: Paul Lagunes, Brian Fried (both of Yale political science) and yours truly recently conducted an experiment in a large Latin American city. The idea was to explore the intersection between corruption and inequality: do public officials behave more corruptly with upper class or lower class individuals? Our experiment involved traffic police and driving infractions, and we found that, conditional on being stopped, lower class individuals were much more likely to be asked to pay a bribe than upper class drivers, who were typically merely warned not to drive in that fashion in the future. Interestingly, not a single traffic ticket was given out during the duration of our experiment!
To help interpret the differential class results, we interviewed police officers in the city to get a sense of what might be driving differential treatments. Based on these interviews, our hypothesis is that upper class drivers were treated differently because of the cops' fear that the former's bureaucratic influence could get them in trouble with their supervisors.
We hope to have a draft of our paper out to a political science or criminology journal soon. I'll keep you posted.
Another benefit of the experimental method is that it allows one to quantify things that are very hard to measure in even the most detailed surveys. This doesn't just include behavioral concepts such as individual preferences, risk aversion, or discount rates, but also phenomenon like corruption, where survey respondents may be loath to reveal their true history of actions due to fears of legal ramification.
Experiments looking at corruption are slowly growing in number. Just recently, I read a paper (no links available) by two Yale political science graduate students looking at the effects of the Indian Right to Information act versus corrupt practices versus the by-the-books apply and wait method in helping slum dwellers in New Delhi receive government ration cards, which serves as a form of ID as well as a means for accessing fair price food shops. In order to get a ration card, individuals have to fill out an application and prove that they meet a particular means test (i.e., their income must be below some threshold). The authors found that nothing greased the wheels quite like corruption, but the Right to Information request did allow individuals to get their ration cards reasonably quickly. Not a single member of the control group, who merely filled out an application for the car, received a ration card even some 7 months after the experiment began.
This experiment is similar in spirit to one recently published in the Quarterly Journal of Economics, which considers the influence of corruption in obtaining a driver's license in India. From the abstract:
We study the allocation of driver's licenses in India by randomly assigning applicants to one of three groups: bonus (offered a bonus for obtaining a license quickly), lesson (offered free driving lessons), or comparison. Both the bonus and lesson groups are more likely to obtain licenses. However, bonus group members are more likely to make extralegal payments and to obtain licenses without knowing how to drive. All extralegal payments happen through private intermediaries ("agents"). An audit study of agents reveals that they can circumvent procedures such as the driving test. Overall, our results support the view that corruption does not merely reflect transfers from citizens to bureaucrats but distorts allocation.
Some self-promotion: Paul Lagunes, Brian Fried (both of Yale political science) and yours truly recently conducted an experiment in a large Latin American city. The idea was to explore the intersection between corruption and inequality: do public officials behave more corruptly with upper class or lower class individuals? Our experiment involved traffic police and driving infractions, and we found that, conditional on being stopped, lower class individuals were much more likely to be asked to pay a bribe than upper class drivers, who were typically merely warned not to drive in that fashion in the future. Interestingly, not a single traffic ticket was given out during the duration of our experiment!
To help interpret the differential class results, we interviewed police officers in the city to get a sense of what might be driving differential treatments. Based on these interviews, our hypothesis is that upper class drivers were treated differently because of the cops' fear that the former's bureaucratic influence could get them in trouble with their supervisors.
We hope to have a draft of our paper out to a political science or criminology journal soon. I'll keep you posted.
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