A Study on the Causal Effects of Childbirth on Maternal Labor Supply in Korea

Cheolsung Park (Hanyang University) and Yuyeong Son (Korea Institute of Finance)

발행년도 2023 / Vol 39 / No 1

We estimate the causal effect of additional childbirth on mothers’ probability of working by using the two-stage least squares estimation method. Samples of mothers drawn from the 10%–20% Restricted Access Samples of the 2000, 2005, 2010, and 2015 Censuses are used. We use children’s gender composition as the instrumental variable for childbirth. We find that additional childbirth had significantly adverse effects on mothers’ probability to work up to 2010, but it is no longer likely to be the case. The ordinary least squares estimates still show a strong negative correlation between childbirth and maternal labor supply, which, our results indicate, is driven mainly by endogenous self-selection. We find that the labor supply of less-educated mothers is more adversely affected by childbirths.   

Regression Discontinuity with Integer Score and Non-Integer Cutoff

Myoung-Jae Lee (Korea University), Hyae-Chong Shim (Korea International Trade Association) and Sang Soo Park (Korea University)

발행년도 2023 / Vol 39 / No 1

In regression discontinuity (RD), the treatment is determined by a continuous score G crossing a cutoff c or not. However, often G is observed only as the ‘rounded-down integer S’ (e.g., birth year observed instead of birth time), and c is not an integer. In this case, the “cutoff sample” (i.e., the observations with S equal to the rounded-down integer of c) is discarded due to the ambiguity in G crossing c or not. We show that, first, if the usual RD estimators are used with the integer nature of S ignored, then a bias occurs, but it becomes zero if a slope symmetry condition holds or if c takes a certain “middle” value. Second, the distribution of the measurement error e G S = - can be specified and tested for, and if the distribution is accepted, then the cutoff sample can be used fruitfully. Third, two-step estimators and bootstrap inference are available in the literature, but a single-step ordinary least squares or instrumental variable estimator is enough. We also provide a simulation study and an empirical analysis for a dental support program based on age in South Korea.