Many studies examine the importance of teachers in students' learning, but few exist on the contribution of principals. We measure the effect of principals on gains in primary test scores in North Carolina and estimate the standard deviation of principals' value added to be 0.12 -0.17. We find...

This study assesses the relationship between sleep quality and academic achievement. We survey college students about their sleep quality by means of the Pittsburgh Sleep Quality Index (PSQI) before the start of their first exam period at university. PSQI scores are matched with course marks in...