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.
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?
Back in 1999, Mr. Levitt was trying to figure out why crime rates had fallen so dramatically in the previous decade. He was struck by the fact that crime began falling nationwide just 18 years after the Supreme Court effectively legalized abortion. He was struck harder by the fact that in five states crime began falling three years earlier than it did everywhere else. These were exactly the five states that had legalized abortion three years before Roe v. Wade.
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