The ELEMENT study dealt with determinants of academic achievement in Berlin. It was carried out in Berlin, where some of the pupils started at a Gymnasium after the 4th grade, while others stayed in primary school until 6th grade and started at different schools after the 6th grade. Factors correlated with academic achievement tend to be intercorrelated (that means that they are also correlated with other factors that determine academic achievement). The number of books owned by a pupil's parents, for example, is correlated with the parents' education. Because of this Multiple Regression Analysis was used. Multiple Regression allows us to understand the influence of one variable when the other variables are held fixed.