The sharp drop in violent crime during the 1990s is one of the big stylized facts social scientists of all sorts have been grappling with. Relatively recent work in this area has led to some surprising findings. I'm sure you are all aware of the Freakonomics finding that the legalization of abortion in the 1970s may be associated with the precipitous drop in crime (see below for more and here if you aren't familiar with this finding).
I recently read another equally startling paper by Jessica Wolpaw Reyes of Amherst, who contends that environmental policy driven decreases in childhood exposure to lead during the 1970s can explain over half of the decline in violent crime! Here's the main idea:
There are substantial reasons to expect that a person's lead exposure as a child could affect the likelihood that he might commit a crime as an adult. Childhood lead exposure increases the likelihood of behavioral and cognitive traits such as impulsivity, aggressivity, and low IQ that are strongly associated with criminal behavior. Under the 1970 Clean Air Act, lead was almost entirely removed from gasoline between 1975 and 1985...As each [of the cohorts born during this time period] approaches adulthood, the sharp declines in lead exposure that occurred between 1975 and 1985 would be revealed in the behavior as adults.
While that pretty much hints at the author's empirical strategy, definitely read the paper if you are interested in learning more about the econometrics. I just finished it and it seems like good science to me.
Other links:
1. For more on the short and long term effects of early life exposure to lead, check out these other papers by Prof Reyes.
2. Levitt and Dubner at the Freakonomics blog have put up a video which explores how the former developed his thesis on the abortion-crime link. A bit earlier in this space, I commented about how great it is to follow an analyst through his/her argument and understand the genesis of cool ideas. Here is your chance to do just that.
3. My aunt just started a blog, called "Spotlight" (included under links). It is as informative, insightful and funny as she is. Here is a sample, from an entry about her recent trip to Cambodia:
Most of my friends in California wondered why we picked Cambodia to visit. Despite the fact that we have three biological children and have our hands full taking care of them, the first question they popped was "Are you going there to adopt?" I quickly pushed aside thoughts of putting up some of my own children for adoption in Cambodia, and replied quite seriously that first there was Angkor Wat, and then quite a few other ancient ruins, which my husband and I dig (metaphorically, that is).
You'll notice the Paul Simon quote on the left hand side of her blog. I had my first exposure to "Western music" during a 1987 trip to India, when my blogger aunt (a very able musician herself) opened my eyes to the brilliance of Paul Simon. His album, Graceland, swept the then still relevant Grammys and won a great deal of critical acclaim.
I remember listening to her walkman at night, thinking about the "boy in the bubble, and the baby with the baboon heart," concepts that brought both wonder and fear to a very young soul. About eight years later, Graceland became the very first CD of my nascent music collection. Just last week, I listened to Paul's poetry on my way back from Cape Town (which is appropriate, given that Graceland is an amalgam of Western and African sounds). And now, I am reading the quotation from "Call me Al," which happens to be my all time favorite bit of lyrics.
Hmm...a bit of a digression I guess. But its amazing how one person's simple gesture to entertain an irritating kid can continue to resonate even as that kid has become an adult (the last part, according to my parents, is debatable).
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