Course Instructor Grades Syllabus Links 1. Increased over 1980s into mid-1990s. Falling again since then. Persistence of gaps in educational achievement Large ethnic gaps in test scores Fell until late 1980s. Not clear why gap has widened since then.
Achievement gap supports human capital explanation.
Increasing returns to cognitive skills Results from wage studies using AFQT scores Also supports statistical discrimination explanation. But is not consistent w failure of earnings gaps to fall after late 1970s.