One third of US children are overweight. Childhood obesity is strongly associated with academic performance, predicts obesity in adulthood, and may be easier to modify than adult weight. Parents who are unaware their children are overweight may impede healthier weight ranges. We consider an informational intervention of New York City’s obesity report cards using a regression discontinuity design framework. To a surprising degree, discontinuous assignment rules are commonplace in allocating program services and shaping clinical care decisions by health care providers. Regression discontinuity designs offer a relatively untapped methodological approach for isolating causal effects, particularly as they relate to health.

Abstract

US schools increasingly report body mass index (BMI) to students and their parents in annual fitness “report cards.” We obtained 3,592,026 BMI reports for New York City public school students for 2007–2012. We focus on female students whose BMI puts them close to their age-specific cutoff for categorization as overweight. Overweight students are notified that their BMI “falls outside a healthy weight” and they should review their BMI with a health care provider. Using a regression discontinuity design, we compare those classified as overweight but near to the overweight cutoff to those whose BMI narrowly earned them a “healthy” BMI grouping. We find that overweight categorization generates small impacts on girls’ subsequent BMI and weight. Whereas presumably an intent of BMI report cards was to slow BMI growth among heavier students, BMIs and weights did not decline relative to healthy peers when assessed the following academic year. Our results speak to the discrete categorization as overweight for girls with BMIs near the overweight cutoff, not to the overall effect of BMI reporting in New York City.