Do Test Score Gaps Grow Before, During, or between the School Years? Measurement Artifacts and What We Can Know in Spite of Them

A classic question in sociology is whether test-score gaps between advantaged and disadvantaged children originate inside or outside schools. One approach to this question is to ask: (1) How large are gaps when children enter school? (2) How much do gaps grow later on? (3) Do gaps grow faster during school or during summer? Confusingly, past research has given discrepant answers to these basic questions. We show that questions about gap growth...