Value-added estimates, as one component of teacher evaluations, offer important information for teachers and administrators, and their reliability is roughly on par with performance estimates used in other fields, scholars conclude in a report released by the Washington-based Brookings Institution.
While an imperfect measure of teacher effectiveness, the year-to-year correlation of value-added estimates of teacher effectiveness is similar to predictive measures for informing high-stakes decisions in other fields, the report says. 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 of baseball talent.
Statistical predictions in those fields are imprecise, too, but they predict larger differences across performers than other measures and so are used, the authors write.
