Research: Value-added measures can inaccurately rate teachers

The fact that part of our new IMPACT teacher evaluations is based on student test scores, this study matters. New research shows that the value-added measures used in some teacher evaluations to measure student growth over time can be inaccurate, Washington Post blogger Valerie Strauss writes. There is a 25% chance that an average teacher could be identified as poor when using three years of data, according to a report by Mathematica Policy Research. That rate climbs to 35% if only one year of student data is studied. The Washington Post/The Answer Sheet blog