Achievement Scores and Educational Objectives

How should achievement scores be used to evaluate public schools? Most large-scale studies have relied on school or program averages alone, overlooking many important educational objectives. Theoretically, objective functions for achievement scores should be constructed; practically, they cannot be. However, a number of easily computable statistics of the intraschool distribution of both uncontrolled and residual scores can be used that have intuitive links to educational objectives like achievement relative to student backgrounds, equality, mobility, the equalizing ability of the school, success with exceptional children, the provision of specific levels of skills, and others. Several of the proposed measures are explored empirically, and nonschool factors do not explain school variation along these measures well. There is also evidence that some schools consistently equalize student scores more than background factors or chance would predict. Recommendations are given for the practical application of the measures in government accountability systems.