Does the early bird catch the worm? The effect of school starting age on educational attainment and labor market outcomes: Evidence from Chinese urban twins data

This paper estimates the effects of school starting age (SSA) on educational attainment and labor market outcomes by using unique urban adult twins data from China. Ordinary least squares (OLS) estimates indicate that late enrollment in primary school lowers years of education, earnings, wage rate, and probability of employment. However, when we use the within-monozygotic (MZ)-twin fixed effects method to exclude unobservable endowments and family factors, the effects of SSA on years of education become less negative. For earnings, wage rate, and the probability of employment, the within-twin fixed effects estimates become insignificant. The results indicate that a one-year delay in primary school starting age lowers schooling by 0.51 years but does not affect earnings, wage rate, or probability of employment. The difference between OLS and within-MZ-twin fixed effects estimates indicates that the negative return to SSA is due to unobservable family variables and omitted individual-specific endowments. We further find that the earlier primary school starters fail to obtain a level of education with high return. Specifically, early birds do not have a high probability of getting a vocational school degree or above.