Research

Abstract:

I examine the persistence of old-for-grade effects on social-emotional skills, measured by self-esteem, friendships, learning approaches, and goal-setting mindsets, from middle through high school. Students who are older at school entry often exhibit better skills than their younger peers near school entry, but how these gaps evolve through secondary education remains less understood. Exploiting a fuzzy regression discontinuity design and the unique contexts of Seoul Education Longitudinal Study 2010 (SELS), I find that old-for-grade girls demonstrate higher self-esteem, while boys show no significant differences. The results also suggest that old-for-grade girls maintain closer friendships and more effective learning approaches. To separate developmental age differences—a potential channel of fadeout—I reconstruct outcome variables to measure skills at the same age. The results indicate that relative age, rather than developmental age differences, is the primary driver of old-for-grade effects.

Abstract:

This paper exploits unique random school assignments in Seoul to examine the effects of single-sex middle schools on students' social-emotional skills and academic achievement. Controlling for sixth-grade baseline measures and elementary school fixed effects, I find that boys in all-boys schools show improved self-esteem and learning approaches compared to their counterparts in coeducational schools. Additionally, all-boys schools enhance boys' test scores in math and English. Conversely, girls in all-girls schools do not consistently experience improvements in social-emotional skills, though there is suggestive evidence of higher test scores compared to the girls in coeducational schools. These findings indicate that single-sex schools have differential effects on girls and boys, potentially leading to differing skill sets that may influence their future outcomes.

• The Two-Parent Privilege and Spillover Effects on School Peers (with Eunju Lee)