'Slender' is how researchers Michael Podgursky and Matthew Springer characterize the existing research on performance pay in a paper out this month. The choice of adjective is oddly gracious, even genteel, given that the context is teacher pay reform, a veritable movement these days, swirling with hype, and with federal and state spigots now open.

Podgursky and Springer, writing for the newly launched National Center on Performance Incentives, offer probably the best summary to date of the history of teacher pay. This includes the failed merit pay movement in the 90s, where performance pay can now be found, how much it costs, how high are the payouts, and how performance is being measured. Of particular interest is a clear and comprehensive review of the 'slender' empirical research, consisting of only nine studies on the subject. Still, considered together, the results are compelling. Seven of the nine found positive results; two found just mixed results, but none found negative results. However, five of these studies looked at pay programs outside the United States, which unfortunately means they're likely to get just a quick sniff before being summarily discarded for their irrelevance.