Use of the average age ratio method in analyzing age heaping in censuses: The case of China

Based on the methods of the average period age ratio and the average cohort age ratio, this study systematically assesses age heaping or digit preference in all population censuses of China. Our study finds that the overall age heaping was relatively low in the Chinese censuses; however, there was a notable preference for ages ending with zero after age 50 in the first two censuses, despite a weakening trend over time. Our study further shows that age heaping in China’s censuses is likely associated with age-related policies such as those on late marriage and retirement. As shown in the study, the average age ratio method can be an alternative of the Whipple’s Index and be improved if the size of birth cohort was taken into account when the number of births is generally reliable.