Explained: Regression analysis
Regression analysis. It sounds like a part of Freudian psychology. In reality, a regression is a seemingly ubiquitous statistical tool appearing in legions of scientific papers, and regression analysis is a method of measuring the link between two or more phenomena. Imagine you want to know the connection between the square footage of houses and their sale prices. A regression charts such a link, in so doing pinpointing “an average causal effect,” as MIT economist Josh Angrist and his co-author Jorn-Steffen Pischke of the London School of Economics put it in their 2009 book, “Mostly Harmless Econometrics.” To grasp the basic concept, take the simplest form of a regression: a linear, bivariate regression, which describes an unchanging relationship between two (and not more) phenomena. Now suppose you are wondering if there is a connection between the time high school students spend doing French homework, and the grades they receive. These...