Equal opportunities for all? Analyzing within-country variation in school effectiveness

The present study addresses the equality of school effectiveness across schools. One central aim of compulsory education is for students to learn equally well at all schools in a country even if these schools differ in terms of student composition. However, measuring equality of learning gains independently from selection effects usually requires longitudinal data. This study suggests a different approach and proposes a new measure for the equality of school effectiveness across schools. We applied a two-level regression discontinuity approach to estimate the between-school variation in added-year effects on mathematics and science achievement that result from an additional year of schooling, after controlling for the effects of age and student selection - i.e., between-school differences in achievement levels. We utilized data from a total of 13 samples. These stemmed from Nordic and other European countries, which assessed students from two adjacent grades at the same schools. The samples stemmed from TIMSS 1995 and 2015 and both primary and secondary school levels. The main findings indicated that although schools differed in initial achievement levels in all samples, schools in some countries, such as Norway and Cyprus, attained a high degree of equality of school effectiveness - i.e., of the effect of an additional year of schooling. Despite the fact that schools with a more privileged student composition had higher achievement levels than less privileged schools, their school effectiveness did not usually differ significantly. Both age and an additional year of schooling resulted in positive effects on mathematics and science achievement, however, effect sizes differed considerably between the 13 samples. We discuss the implications of the proposed school effectiveness measure, which is based on a regression discontinuity approach. We conclude that countries, such as Nordic ones, should consider extending their participation in international large-scale assessments with additional grades from the same schools in future cycles. This design would enable a multitude of robust school effectiveness studies in the future.