The influence of social class on educational achievement is much greater in western Germany than it is in eastern Germany (former GDR). An analysis of PISA data on Gymnasium pupils for the year 2000 showed that, while in western Germany the child of an academic was 7.26 times as likely as that of a skilled worker to attend, in eastern Germany a child from an academic family was only 2.78 times as likely as a working-class child to attend. The reasons for this were unclear. Some people believed that immigrants were responsible, because more uneducated immigrant families lived in western than in eastern Germany. This assumption however could not be confirmed. The difference between east and west was even stronger when only ethnic German children were studied.