Estimated total number of second children based on three sources: the case of the city of Chengdu, Sichuan, China, for the year 2018

ABSTRACT The total number of registered second children may be underestimated due to repetitions, omissions, and counting errors. The three-source estimator provides a more accurate value. It is based on the household registration list, a sample survey list, and the hospital birth list. It avoids the correlation bias inherent in the estimator based on a sample survey and household registration or hospital births. Its expression is adapted to the estimation of the total number of second children. In the case of Chengdu, it allows for estimating the total number of second children at 99,633, which is substantially higher than the reported number of 96,105 obtained by counting registrations alone.