But every curve, as we just learned from Newton, is pretty close to a line. That’s the idea that drives linear regression, the statistical technique that is to social science as the screwdriver is to home repair. It’s the one tool you’re pretty much definitely going to use, whatever the task. Every time you read in the newspaper that people with more cousins are happier, or that countries that have more Burger Kings have looser morals, or that halving your intake of niacin doubles your risk of athlete’s foot, or that every extra $10,000 of income makes you 3% more likely to vote Republican,*
...more
