Adjusting school-leaving grades for student selection

School-leaving grades are predictive for study success in many subjects, although grading standards often differ between regions or school types. The German Constitutional Court compelled the legislature to implement a procedure for adjusting the grades between federal states in Germany. We propose using state-specific percentile ranks, as we can show that this homogenises the chance of admission between federal states. In addition, the percentile ranks also lead to a more similar predictive validity in terms of study success in undergraduate medicine in Hamburg. Furthermore, the percentile ranks would make it possible to adjust the grades of other groups whose grades are difficult to compare.