I also wonder what this study means for champions of performance pay. The logic of merit pay suggests successful teachers need an incentive to stay put. The study suggests they’re already doing so.
One has to think that in the medium term we are going to get better data about what actually happens in schools, and in the process, many of the naive assumptions of the reformers currently pushing for better data will be overturned. "Good" teachers will be moved into "bad" schools and become "bad" teachers. Then what?