Differential Student Attrition and Differential Exposure Mask Effects of Problem-Based Learning in Curriculum Comparison Studies

PURPOSE: Studies that compare the effects of problem-based and conventional medical curricula on student performance generally show no significant differences. However, curriculum comparison studies are at best quasi-experimental, so they are prone to forms of selection bias. The purpose of this study was to reanalyze data from such comparisons by controlling for two potential biases: differential student attrition and differential exposure.