The issue of our day is: How do we measure teacher effectiveness? Most of the studies by economists warn that there is a significant margin of error in “value-added assessment” (VAA) or “value-added modeling” (VAM). The basic idea of VAA is that teacher quality can be measured by the test-score gains of their students. Proponents of VAA see it as the best way to identify teachers who should get merit pay and teachers who should be fired. Critics say that the method is too flawed to use for high-stakes purposes such as these.
The bulk of studies warn about the inaccuracy and instability of these measures, but the Gates Foundation recently released a study called “Measures of Effective Teaching” that supports the use of VAA and VAM. As is customary for the Gates Foundation, it hired an impressive list of economists at institutions across the nation to give the gloss of authority to its work. Among its key findings was this one: “Teachers with high value-added on state tests tend to promote deeper conceptual understanding as well.” Ah, said the proponents of measuring teacher quality by the rise and fall of student test scores, this study vindicates these methods and effectively counters all those cautionary warnings.