How Did It Get This Way? Disentangling the Sources of Teacher Quality Gaps Across Two States

We use longitudinal data from North Carolina and Washington to study the extent to which four processes—teacher attrition from each state workforce, teacher mobility within districts, teacher mobility across districts, and teacher hiring—contribute to “teacher quality gaps” (TQGs) between advantaged and disadvantaged schools. We first replicate prior findings documenting inequities in each of these processes using different measures of student disadvantage (race and poverty) and teacher quality (experience, licensure test scores, and value added) and then develop and implement a simulation to assess the extent to which each process contributes to observed TQGs in each state. We find that all four processes contribute to TQGs but also document considerable heterogeneity in the extent to which each process contributes to the different TQG measures. For example, patterns in teacher attrition and mobility contribute more to TQGs measured by teacher experience, while patterns in teacher hiring explain the majority of TQGs measured by teacher licensure test scores and value added.