More "One Study Does Not a Policy Make"
Bruce Baker has weighed in on the big study, reported in the New York Times, that attempts to tie teacher ratings using standardized test scores to students' future earnings:
First and perhaps most importantly, just because teacher VA scores in a massive data set show variance does not mean that we can identify with any level of precision or accuracy, which individual teachers (plucking single points from a massive scatterplot) are “good” and which are “bad.” Therein exists one of the major fallacies of moving from large scale econometric analysis to micro level human resource management.Second, much of the spin has been on the implications of this study for immediate