Achievement gaps are one of education’s most important policy metrics. Gaps between boys and girls, as well as white and racial minority students, are often used to measure the effectiveness and fairness of the education system at a given point in time, over the course of decades, and as children progress through school. Major policy initiatives related to accountability, assessment, and funding are partially motivated by a desire to close gaps.
As is so often the case, however, estimates of achievement gaps are not as straightforward as practitioners and policymakers might like. Gaps result from the sum total of students’ schooling, after-school activities, home life, and neighborhood experiences. Further, gaps are not measures of intelligence or ability, but of performance. Therefore, observed scores are impacted by factors that adults control (like what students are taught), and by factors that may be unrelated to achievement (like motivation to perform).