Why the economics of minimum wage increases are so tough to measure

Last week, several researchers at the Federal Reserve posted an analysis of the minimum wage in New York state. In the grand sweep of the research and debate done on the minimum wage, both the blog post and the dispute it kicked up were minor blips. But as a microcosm for that grander debate, it was actually rather instructive.

Basically, a trio of researchers at the Federal Reserve branch of New York spotted a chance for a natural experiment. Over the last few years, New York state has passed a...