Scholars back value-added’s value

Value-added data on student performance adds value to teacher evaluations, concludes a Brookings report by a group of well-respected scholars.  “We conclude that value-added data has an important role to play in teacher evaluation systems, but that there is much to be learned about how best to use value-added information in human resource decisions.”

At Teacher Beat, Stephen Sawchuk summarizes:

While an imperfect measure of teacher effectiveness, the correlation of year-to-year value-added estimates of teacher effectiveness is similar to predictive measures for informing high-stakes decisions in other fields, the report states. Examples include using SAT scores to determine college entrance, mortality rates and patient volume as quality measures for surgeons and hospitals, and batting averages as a gauge for selecting baseball talent.

Statistical predictions in those fields are imprecise, too, but they’re able to predict larger differences across providers than other measures and so are used, the authors write.

The traditional method of evaluating teachers identifies nearly all as effective, the Brookings authors write. That’s both inaccurate and harmful to students.

“When teacher evaluation that incorporates value-added is compared against an abstract ideal, it can easily be found wanting in that it provides only a fuzzy signal. But when it is compared to performance information in other fields in other fields or to evaluations of teachers based on other sources of information, it looks respectable and appears to provide the best signal we’ve got.”

By contrast, the Economic Policy Institute and the National Academy of Sciences issued reports criticizing the reliability of value-added measures and arguing the data should not be used to evaluate teachers.