|Hongbin Li, Junsen Zhang
This paper measures the eﬀect of the unique one-child policy on fertility by exploring the natural experiment that has been created by China’s special aﬃrmative birth control policy, which is possibly the largest social experiment in human history. Because the one-child policy only applied to Han Chinese, but not to ethnic minorities, we construct a diﬀerences-in-diﬀerences estimator to identify the eﬀect of the policy on fertility. Such a natural experiment is a rare opportunity, whether for the analysis of the eﬀect on fertility or for the analysis of economics in general. Using two rounds of the Chinese Population Census, we ﬁnd that the one-child policy has had a large eﬀect on fertility. The average eﬀect on the post-treatment cohorts on the probability of having a second child is as large as -11 percentage points. We also ﬁnd that the magnitude is larger in urban areas and for more educated women. Our robustness tests suggest that our diﬀerences-in-diﬀerences estimates of the eﬀect of the one-child policy are not very likely to be driven by other policy or socio-economic changes that have aﬀected the Han and the minorities diﬀerently. The identiﬁcation strategy that is based on this unique natural experiment can potentially be used to break endogeneity in other economic relationships, such as the eﬀect of one more child on parental labor supply, child quality, and the stability of marriage.