Bringing Empirical Evidence to Economics

Paul Krugman has a great tribute to Alan Krueger, the brilliant Princeton economist who died, apparently by suicide, last weekend:

I thought I knew Alan reasonably well and never saw a hint that something like this might be coming. But people’s lives often feel very different from the inside than they look on the outside.

What I can talk about is Alan’s work and why it mattered so much to other economists, myself very much included. For his research arguably did more to change how we view the economy than that of any other modern economist.

Alan’s most influential, paradigm-shifting work was his 1992 study with David Card on the effects of minimum-wage increases.

Before Card and Krueger, most economists just assumed that raising the minimum wage leads to lower employment. But Card and Krueger realized that this was a proposition you can test. Their initial study compared employment in New Jersey and Pennsylvania before and after New Jersey raised its minimum wage. And they found no adverse effect on employment — if anything, a small rise in New Jersey relative to its neighbor.

This study opened a new frontier in economic research. Economics is always bedeviled by the lack of controlled experiments; there are so many things going on in the economy that it’s hard to tell what’s causing what. But unilateral state wage hikes amount to natural experiments that tell you far more than standard economic methods.

Furthermore, this was a method that could be replicated many times, and has been over the years, right up to the recent round of minimum wage increases in a number of cities. And the preponderance of the results have confirmed Card and Krueger’s initial finding: raising minimum wages has far less negative impact on jobs than standard economics would have predicted.

This has implications that go far beyond minimum wages themselves. What Card, Krueger and the research that follows tell us is that labor markets are a lot more complicated than we thought, that market power matters a lot and that there may be much more room for public policy to raise wages in general than Econ 101 would have it.