Monday, October 22, 2007

The Differences Between Men and Women

Larry Summers got in to a lot of trouble conjecturing on this topic, but I think this speech has it about right. But one of the interesting things he wrote:

The first big, basic difference has to do with what I consider to be the most underappreciated fact about gender. Consider this question: What percent of our ancestors were women?It’s not a trick question, and it’s not 50%. True, about half the people who ever lived were women, but that’s not the question. We’re asking about all the people who ever lived who have a descendant living today. Or, put another way, yes, every baby has both a mother and a father, but some of those parents had multiple children.

Recent research using DNA analysis answered this question about two years ago. Today’s human population is descended from twice as many women as men.

I think this difference is the single most underappreciated fact about gender. To get that kind of difference, you had to have something like, throughout the entire history of the human race, maybe 80% of women but only 40% of men reproduced.

Right now our field is having a lively debate about how much behavior can be explained by evolutionary theory. But if evolution explains anything at all, it explains things related to reproduction, because reproduction is at the heart of natural selection. Basically, the traits that were most effective for reproduction would be at the center of evolutionary psychology. It would be shocking if these vastly different reproductive odds for men and women failed to produce some personality differences.

Most men who ever lived did not have descendants who are alive today. Their lines were dead ends. Hence it was necessary to take chances, try new things, be creative, explore other possibilities. Sailing off into the unknown may be risky, and you might drown or be killed or whatever, but then again if you stay home you won’t reproduce anyway. We’re most descended from the type of men who made the risky voyage and managed to come back rich. In that case he would finally get a good chance to pass on his genes. We’re descended from men who took chances (and were lucky).

So one of the main differences between men and women is that men are much bigger risk takers. Why does the image of some redneck saying "hey guys watch this..." come to mind?

Abortion and Crime

Looks like Levitt gets some support for his much maligned theory on abortion and crime. A paper by Anindya Sen finds much the same as he did, but pins it mostly on teens:
Donohue and Levitt (2001) attribute over half of the decline in U.S. crime rates during the 1990s to abortion legalization. This paper conducts similar research by exploiting cross-province time-series variation in Canadian data. The use of Canadian data allows me to separate the effects of teenage abortions from general abortion rates. This distinction is important, as more than a quarter of the drop in violent crime can be attributed to the increase in teenage abortions that occurred after legalization. These results suggest that lower crime rates from abortion legalization are due to better timing of births rather than lower cohort size. They are further substantiated by OLS estimates, which imply that the drop in teenage fertility rates during the 1960s and 1970s is responsible for more than half of the decline in violent crime rates witnessed during the 1990s.

Sunday, October 21, 2007

Health Economics

I'm on sabbatical for the 2007-2008 academic year, retooling so that I can teach ECO 471 - Health Economics when I return. Here are some things I've learned so far:

1. More medical care spending doesn't lead to better health outcomes. This is found in the famous RAND experiments, cross state studies, and cross national studies.

2. The differences across income groups are larger than differences across racial/ethnic groups, but even after controlling for education, and income there are still important racial differences. Quite possibly we have at work

3. Sometimes increasing poverty can improve some heath outcomes.

4. Sometimes medical care is bad for you. After all To Err is Human.

5. Drugs are good, though not universally so. Then there is the problem of me too drugs.

6. Most improvements in life expectancy have been due to improvements in diet and public health, such as clean water, sanitation, etc.

My take away from all this is that there is a lot to improving health outcomes that is unrelated to heath care. It turns out that there are a lot of other factors that are more important. Your friends, the neighborhood you live in, your taste for risky activities.


And I thought it was just used to sell old bike stuff.

“Craigslist has become the high-tech 42nd Street, where much of the solicitation takes place now,” said Richard McGuire, Nassau’s assistant chief of detectives. “Technology has worked its way into every profession, including the oldest.”

Loonie Power

The rising value of the Canadian Dollar has led to cross border labor flows...of strippers.

With the Canadian dollar surging against the U.S. greenback, Robert Katzman is dealing with situations they don't teach in Economics 101.

The owner of five strip clubs in Detroit and Windsor, Ontario, says American dancers are heading to Canada to earn the strengthened Canadian currency, and Canadian customers are heading to Detroit because their dollars go further there. He's fighting back by advertising more in the U.S. and offering free limo service to get Detroit men to visit his Windsor clubs. [...]

Mr. Katzman, the Windsor strip-club owner, is philosophical. He says that, last year, 90% of his dancers were Canadians. About 200 of them drove down from Toronto and Montreal to take advantage of the U.S. dollars American men typically paid with.

This year, he has more American women dancing in his Canadian clubs -- about 160 -- than he has Canadians.

It's a nine-hour trip from Montreal to Windsor, Mr. Katzman explains, and with the loonie as strong as the dollar, the dancers can earn just as much money up there. "As a business decision, it just doesn't make sense," says Mr. Katzman.

Ovulating Strippers

Yes, you read that right. From the latest Economist, ovulating strippers make more money.

“BECAUSE academics may be unfamiliar with the gentlemen's club sub-culture, some background may be helpful to understand why this is an ideal setting for understanding real-world attractiveness effects of human female oestrus.”

No doubt readers of The Economist are equally unfamiliar with this sub-culture, but for Geoffrey Miller of the University of New Mexico, who penned the words above in a paper just published in Evolution and Human Behaviour, such clubs are a field site as revealing of human biology as the Serengeti is of the biology of lions and antelopes. Dr Miller is an evolutionary psychologist—and the author of the theory that the large brains of humans evolved to attract the opposite sex in much the same way that a peacock's tail does. His latest foray, into the flesh-pots of Albuquerque, is intended to investigate an orthodoxy of human mating theory. This is that in people, oestrus—the outward signs of ovulation—has been lost, so that men cannot tell when women are fertile.

This theory is based on the idea that in evolutionary terms it benefits women to disguise when they are fertile so that their menfolk will stick around all the time. Otherwise, the theory goes, a man might go hunting for alternative mating opportunities at moments when he knew that his partner was infertile and thus that her infidelity could not result in children.

However, this should result in an evolutionary arms race between the sexes, as men evolve ever-heightened sensitivity to signs of female fertility. Dr Miller thought lap-dancing clubs a good place to study this arms race, because male detection of female fertility cues would probably translate into an easily quantifiable signal, namely dollars earned. He therefore recruited some of the girls into his experiment, with a view to comparing the earnings of those on the Pill (whose fertility was thus suppressed) with those not on the Pill.

The results support the idea that if evolution has favoured concealed ovulation in women, it has also favoured ovulation-detection in men. The average earnings per shift of women who were ovulating was $335. During menstruation (when they were infertile) that dropped to $185—about what women on the Pill made throughout the month. The lessons are clear. A woman is sexier when she is most fertile. And if she wishes to earn a good living as a dancer, she should stay off the Pill.

The article is here.

Sunday, October 14, 2007

Fucking Fascinating

Steven Pinker proves again to be an uber mensch. He eloquently writes on the nature and taboo of swearing:
When used judiciously, swearing can be hilarious, poignant, and uncannily descriptive. More than any other form of language, it recruits our expressive faculties to the fullest: the combinatorial power of syntax; the evocativeness of metaphor; the pleasure of alliteration, meter, and rhyme; and the emotional charge of our attitudes, both thinkable and unthinkable. It engages the full expanse of the brain: left and right, high and low, ancient and modern. Shakespeare, no stranger to earthy language himself, had Caliban speak for the entire human race when he said, "You taught me language, and my profit on't is, I know how to curse."
I just have to remember to use the F word a bit more judiciously.

Partially Identified Models

I attended another UW-Madison seminar, this one on: "EL Inference for Partially Identified Models: Large Deviations Optimality and Bootstrap Validity". I have to admit, I was hanging on for dear life, understanding maybe 25% of what was going on. But I'm an applied researcher, as long as I can implement it in STATA, who cares? Only kidding...mostly.

I have to admit, I find the issues of partial identification very interesting. I just read a piece by Charles Manski, Identification Problems from the Social Sciences and Everyday Life. I also have read part of his book, Identification Problems in the Social Sciences and, while deeply interested I'm also deeply depressed. I'm pretty sure we don't know anything about anything. Well, maybe that is overly pessimistic, but his fundamental point (pun intended) is that point identification is really impossible except by absurdly tight assumption, we are better off in a world without point identification, but where we merely try to narrow the bounds of identification.

I'm pretty sure this puts him in the same camp as Heckman in regards to the ever popular explosion in the use of IVs. As Manski points out, in many cases we replace bad assumptions with weak instruments, yielding no real improvement in the quality of results we generate.

Think about how big this statement is. If one of the identification problem arises with missing data, something EVERY survey suffers from, then the usual solution of ignoring it but treating it as missing at random, is the first egregious mistake in the process. And that say nothing about any of the other identification issues that inevitably arise.

Now I'm depressed again.

Thursday, October 11, 2007

My Inner Economist

Tapping my inner Economist, I can't help but wonder if this website is dedicated to towns where the sex ratio is askew? Or maybe just towns where the hot chicks are blind? I once told a class I could guess the sex ratio at UW-L was skewed towards females merely by looking at the number of couples where the guy was obviously not as good looking as the girl. They were shocked. I think next time I'll just point them to the hotchicks with douchebags website.