The perils of obsessive measurement

This short essay describes the negative and unlooked-for (but easy to predict) effects of attempting to marry measurement of results with paying people for achieving them. Someone needs to forward it to the U.S. Department of Education, and to a variety of state departments of education. It's a clear, concise explanation of why merit pay is an absolutely abysmal idea, guaranteed to result in poorer outcomes for the students most in need of better ones. It's in the context of the British health care system.