Measuring Up: What Educational Testing Really Tells Us

by Daniel Koretz

It is well known that, on average, the schools serving poor children are of lower quality than those serving students from higher-income families. Resources are more limited in schools in low-income areas, for example, and teaching positions are more likely to be filled by inexperienced and uncertified teachers. Now let’s assume—hardly a risky assumption—that some of these differences among schools matter and that, as a result, many poor students learn less in school and end up less well prepared for college. If that is true, tests designed to estimate how well prepared students are for college should give lower average scores to students from these lower-quality schools, and hence, on average, to low-income children. A valid inference about preparedness for college would require that these students obtain lower scores.