This is an important article, which criticizes and deconstructs the notorious VAM study by Chetty et al. I refer to it as notorious because it was reported on the first page of the New York Times before it was peer-reviewed; it was immediately presented on the PBS Newshour; and President Obama referred to its findings in his State of the Union address only weeks after it first appeared.
These miraculous events do not happen by accident. The study made grand claims for the importance of value-added measures of teacher quality, a keystone of Obama's education policy. One of the authors told the New York Times that the lesson of the study was to fire teachers sooner rather than later. A few months ago, the American Statistical Association reacted to the study, not harshly, but made clear that the study was overstated, that the influence of teachers on the variability of test scores ranged from 1-14%, and that changes in the system would likely have more influence on students' academic outcomes than attaching the scores of students to individual teachers.
I have said it before, and I will say it again: VAM is Junk Science. Looking at children as machine-made widgets and looking at learning solely as standardized test scores may thrill some econometricians, but it has nothing to do with the real world of children, learning, and teaching. It is a grand theory that might net its authors a Nobel Prize for its grandiosity, but it is both meaningless in relation to any genuine concept of education and harmful in its mechanistic and reductive view of humanity.