School Year Length and Student Performance: Quasi Experimental Evidence

This paper investigates the impact of instructional days on student performance. Because school year length is endogenously determined, I estimate the causal impact of school year length through two quasi-experiments that exploit different sources of variation in instructional days. The first identifies school year length’s effect through weather-related cancellations in Colorado and Maryland. Weather-related cancellations are made up at the end of school years, allowing relatively large fluctuations in instructional days within school districts prior to test administration. Because school cancellations are not recorded for past school years, this data limitation is overcome by using two-sample indirect least squares. The second identification strategy takes advantage of state-mandated changes in test-date administration in Minnesota, which moved 5 times in 5 years. The results are similar for either source of instructional day variation: more instructional time prior to test administration increases student performance. The effects are consistent across various thresholds of performance and grade levels. JEL Classification: I20, I28, J08