The Tipping Point That Wasn’t?

“It is an inspirational urban lesson from the 1990’s: take back the streets from squeegee men and drug dealers, and violent crime will plummet. But on Thursday evening, the tipping-point theory was looking pretty wobbly itself.

The occasion was a debate in Manhattan before an audience thrilled to be present for a historic occasion: the first showdown between two social-science wonks with books that were ranked second and third on (outsold only by ‘Harry Potter’). It pitted Malcolm Gladwell, author of ‘Blink’ and ‘The Tipping Point,’ against Steven D. Levitt, an economist at the University of Chicago with the new second-place book, ‘Freakonomics.’

Professor Levitt considers the New York crime story to be an urban legend. Yes, he acknowledges, there are tipping points when people suddenly start acting differently, but why did crime drop in so many other cities that weren’t using New York’s policing techniques? His new book, written with Stephen J. Dubner, concludes that one big reason was simply the longer prison sentences that kept criminals off the streets of New York and other cities.

The prison terms don’t explain why crime fell sooner and more sharply in New York than elsewhere, but Professor Levitt accounts for that, too. One reason he cites is that the crack epidemic eased earlier in New York than in other cities. Another, more important, reason is that New York added lots of cops in the early 90’s.

But the single most important cause, he says, was an event two decades earlier: the legalization of abortion in New York State in 1970, three years before it was legalized nationally by the Supreme Court.” — John Tierney, (New York Times op-ed)

Levitt has a weblog too.

Freakonomics: When Numbers Solve a Mystery

Meet the economist who figured out that legal abortion was behind dropping crime rates: “If Indiana Jones were an economist, he’d be Steven Levitt. The most recent winner of the John Bates Clark award for the best economist under the age of 40, Mr. Levitt is famous not as a master of dry technical arcana but as a maverick treasure hunter who relies for success on his wit, pluck and disregard for conventional wisdom. Mr. Levitt’s typical quarry is hidden not in some exotic locale but in a pile of data. His genius is to take a seemingly meaningless set of numbers, ferret out the telltale pattern and recognize what it means.

It was Mr. Levitt who nailed a bunch of Chicago public-school teachers for artificially inflating their students’ standardized test scores. I’m dying to tell you exactly how he did it, but I don’t want to spoil any surprises. His account of the affair in Freakonomics reads like a detective novel.

The evidence is right there in front of you: Mr. Levitt actually reproduces all the answer sheets from two Chicago classrooms and challenges you to spot the cheater. Then he shows you how it’s done. He points to suspicious patterns that you almost surely overlooked. Suspicious, yes, but not conclusive–maybe there is some legitimate explanation. Except that Mr. Levitt slowly piles pattern on pattern, ruling out one explanation after another until only the most insidious one remains. The resulting tour de force is so convincing that it eventually cost 12 Chicago schoolteachers their jobs.

The Case of the Cheating Teachers would make a fascinating book, but in Mr. Levitt’s hands it is compressed into 12 breathtaking pages. Then he is on to his next adventure–the Case of the Cheating Sumo Wrestlers. Here an entirely different kind of data (the win-loss records from tournaments) gets the Levitt treatment: the identification of a suspicious pattern, a labyrinth of reasoning to rule out the innocent explanations and a compelling indictment.

Then it’s on to another question, and another and another. Were lynchings, as their malevolent perpetrators hoped, an effective way to keep Southern blacks ‘in their place’? Do real-estate agents really represent their clients’ interests? Why do so many drug dealers live with their mothers? Which parenting strategies work and which don’t? Does a good first name contribute to success in life?” (WSJ Opinion Journal)

Sex in the Stone Age:

Pornography in Clay: “New pornographic figurines from the Stone Age have been discovered in Germany. But researchers can’t agree on what the 7,000-year-old sculptures mean. Were our ancestors uninhibited sex fiends, or was reproduction strictly controlled to improve mobility? An increasing number of finds seem to indicate the Stone Age was an orgy of sexual imagination.” (Der Spiegel)

I am not exactly sure why this should surprise us.