Over de validiteit van indicatoren voor schooleffectiviteit: Een kritische beschouwing

On the validity of school performance indicators School performance indicators are generally considered to be important elements in programs for school improvement and external accountability. In this article five indicators are described, of varying origin. Three are in use by the Dutch Inspectorate of Education, while the other two are used mainly for research purposes; four are based on a value-added approach, one on school mean proficiency. The indicators are compared against a frame of six validity criteria, including for instance measurement precision and topicality. It is concluded that all five indicators show shortcomings, be it in varying degree. In the discussion three factors are explored that hamper the measurement of school performance in terms of learning outcomes. Better understanding of school performance indicators requires insight into the process variables that distinguish effective schools from less effective schools. The stronger process variables like teacher qualities and effective learning time are related to school performance indicators, the more valid these indicators are to be considered.