The Gap within the Gap: Finding A Better Measure of Student Disadvantage

Gaps in educational achievement between high- and low-income children are growing. Administrative datasets maintained by states and districts lack information about income but do indicate whether a student is eligible for subsidized school meals. We leverage the longitudinal structure of these datasets to develop a new measure of persistent economic disadvantage. Half of 8th graders in Michigan are eligible for a subsidized meal, but just 14 percent have been eligible for subsidized meals in every grade since kindergarten. These children score 0.94 standard deviations below those never eligible for subsidies and 0.23 below those occasionally eligible. There is a negative, linear relationship between grades spent in economic disadvantage and 8th grade test scores. This is not an exposure effect: the relationship is almost identical in 3rd grade, before children have been differentially exposed to five more years of economic disadvantage. Survey data show that the number of years that a child will spend eligible for subsidized lunch is negatively correlated with her current household income. Years eligible for subsidized meals can therefore be used as a reasonable proxy for income. Our proposed measure can be used in evaluations to estimate heterogeneous effects, to improve value-added calculations, and to better target resources.

Key findings

  1. In Michigan, 60% of students are eligible for free or reduced-price lunch at least once by 8th grade and 14% receive meal subsidies every year they are in school.
  2. Students who receive free or reduced-price lunch every year perform nearly a full standard deviation below their peers who never receive meal subsidies on standardized math tests, a gap that is between 35% and 40% larger than the achievement gap between those who receive free or reduced-price lunch in a given year and those who do not, even after accounting for student and school characteristics.
  3. Among students traditionally classified as low-income, there is an achievement gap of nearly a quarter standard deviation between those receiving meal subsidies every year and those who receive subsidies only in some years.