Does Obesity Lead to Poor School Performance? Estimates from Propensity Score Matching

Hongyun Han, University of Wisconsin-Madison

High body weight is negatively associated with test scores among elementary and middle school students. Are these negative outcomes due to preexisting differences, or are they a casual effect of obesity? To better understand the causal mechanisms underlying this pattern, I use a propensity score matching approach to control for biases from observable variables, and conduct sensitivity analysis to assess the impact of biases from unobserved variables. Using data from the Early Childhood Longitudinal Study, the matching models reveal that obese eighth graders, on average, score 0.17 standard deviations lower in reading and 0.15 standard deviations lower in math, a reduction roughly equivalent to one sixth of the racial achievement gap. Differences between obese and normal-weight children decline slightly after adjusting for missing values. Findings from sensitivity analyses indicate that unmeasured variables would need to increase the odds of becoming obese by at least 20 percent to change the conclusion.