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Stanford’s Eric Bettinger and his research team found that students who won a lottery for a voucher in Colombia were 17% more likely to complete high school on time than students who lost the lottery. The study, released in July, used a method of random assignment to compare apples to apples. So it isn’t because of selection bias that lottery winners earned 8% more than lottery losers by the time they turned 33. It’s because their parents were allowed to choose schools that were better fits for their children.
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