Determining the optimal age at which a child should enter school is a controversial topic in education policy. In particular, German policy makers, pedagogues, parents, and teachers have since long discussed whether the traditional, established age of school entry at 6 years remains appropriate....

Data from 31 countries participating in the Programme for International Student Assessment (PISA) is used to estimate education production functions for reading literacy. The Analysis suggests that the probability of finding statistically significant and correctly signed class size effects...