The Manhattan Institute's SchoolGrades.org evaluates and assigns grades, using reading and math test scores, to U.S. schools and compares schools across their respective states and to other countries. They apparently use a four-step process: (1) average two state test scores; (2) “norm” these results to the NAEP exam; (3) make an adjustment to this national “normed” measure using free and reduced price lunch data to account for SES; and (4) “norm” these results to the international PISA exam. The claim is that this process allows a parent to compare a local school to schools in their state and to other countries like South Korea and Lithuania. But the unsubstantiated norming chain is too tenuous and the results are overly extrapolated to be of any useful value. The website does not explain how international scores are “normed” (equated) to the national standard they developed or how letter grades were determined, nor does it explain how free and reduced price lunch counts are used to make socioeconomic adjustments. While there is considerable equating research available, none is cited. Further, the reliance on aggregated test scores is far too narrow a base to serve as a useful evaluation of schools. Thus, the website’s approach to evaluating schools fails on technical grounds and, just as importantly, it fails to understand and consider the broader purposes of education in a democratic society.
Manhattan Institute for Policy Research