From the National Educational Policy Center:
The Bill & Melinda Gates Foundation’s “Measures of Effective Teaching” (MET) Project seeks to validate the use of a teacher’s estimated “value-added”-computed from the year-on-year test score gains of her students-as a measure of teaching effectiveness. Using data from six school districts, the initial report examines correlations between student survey responses and value-added scores computed both from state tests and from higher-order tests of conceptual understanding. The study finds that the measures are related, but only modestly. The report interprets this as support for the use of value-added as the basis for teacher evaluations. This conclusion is unsupported, as the data in fact indicate that a teachers’ value-added for the state test is not strongly related to her effectiveness in a broader sense. Most notably, value-added for state assessments is correlated 0.5 or less with that for the alternative assessments, meaning that many teachers whose value-added for one test is low are in fact quite effective when judged by the other. As there is every reason to think that the problems with value-added measures apparent in the MET data would be worse in a high-stakes environment, the MET results are sobering about the value of student achievement data as a significant component of teacher evaluations.
On the same topic, here’s another piece from the Shanker Institute and reported in blogger Valerie Strauss’s column in the Washington Post…By the way, Strauss is always a great read.