The relationship between the hukou system and the population census is quite close across the whole process of census performance. In the three most recent censuses, hukou status is one of the most important references to decide whether and where to enumerate a person. At the preparation stage, the hukou registers constitute the basis for dividing enumeration areas. The Census Offices obtain the lists of targeted households in each enumeration area based on the hukou registers and assign tasks to enumerators within their regions. Recognising their compensating errors caused by the omissions and duplications, the State Council decided to conduct a cleanup program for months in advance of the 1982 census. This could be regarded as a large-scale census pre-test or an informal census and it has been a necessary procedure before the census ever since. Several months before the census, according to the State Council’s directive, millions of census-takers helped police in each enumeration area to inspect the hukou registers household by household. During this process, they devoted much effort to correcting mistakes in hukou registers, both those kept in police stations and those in households, and matched each person with his or her household register. Subsequently, the Census Offices at each level would update the household lists and reassign the tasks for each enumeration area.
At the census-taking stage, enumerators conducted household interviews according to the allocated household lists to inquire about household information and any changes that had occurred in the preceding year. This would make the census count a little easier than expected and ensure that the census basically reflected the number
and distribution of the population. Because of the several months time gap between the cleanup program and the formal census enumeration, there could be changes in a large number of households, so once enumerators found discrepancies between the interview results and the updated hukou register, they are directed to investigate the household again and carry out a cross-check with other sources. After the census, the census results were used to update and improve the household registration system. However, the population census is the only opportunity to greatly improve the increasingly deteriorated hukou system for each ten-year period.
Considering there was such a close relationship, to a great extent the quality of the census synchronised with that of the hukou statistics. Indeed, the rather complete hukou registrations and pre-census cleanup program ensured the success of the 1982 census and 1990 censuses (Zhang and Cui 1994; Zhou 1986), while the weakened system was partly blamed for obvious undercounts in the 2000 census (Zhang and Cui 2003). Certainly, the effects of the hukou system on the census appeared in many aspects, for example, many authors suggested that the hukou-based census criteria of residence and occupation had already not been able to reflect changing realities (Banister 1984; Zhou and Ma 2003). Moreover, the definition of individual household and collective household also affected the census operation (Zhao 2001).
The family planning statistics rely on the hukou registers to decide their targets. The current statistical system has been in effect since 1990, when the SSB and SFPC jointly issued a circular on Practical Stipulations of Family Planning Statistics (Peng 1997). Under this requirement, a married woman is supposed to be enumerated at her permanent residence, and her newborn is enumerated following her registration. However, once a married woman temporarily migrates out, she should be enumerated at the current residential location if she has left her permanent residence for more than six months, otherwise still at her permanent residence. This procedure was intended to distinguish the responsibility of family planning institutions between immigration and emigration areas because of the continual increase in population mobility. However, it actually increased the instances of non-registration. As with the census performance, it was difficult to distinguish a woman’s supposed registration residence by her permanent residence and the six-month duration since her leaving that residence; this contributed to common accidental misreporting.
Moreover, because the number of births is one of the most important evaluation indicators for program performance everywhere, the family planning administrations at both a migrated woman’s current residence and her permanent residence have strong incentives to deliberately miss these women, and potentially their births.
There is also a very close relationship between the hukou system and sample surveys, including the sample census. The only available statistics for all population below the provincial level during the intercensal period are the hukou statistics. Although the annual survey provides CBR series in the preceding year, they are only available at the national and provincial levels. Therefore, either the SSB annual survey or the SFPC retrospective survey must rely on them to draw the sampling frame. As the focus of both the SSB and SFPC surveys is fertility, the CBR in the preceding year is an essential index to decide the sample size. However, both of them have to draw on the hukou statistics’ recorded birth rate, though seriously biased, to decide the sample size and ultimate sampling units. During the 1980s, the SSB used the surveyed birth rates to estimate the annual number of births based on the hukou registered population, which resulted in the underestimate of births (Hu 1994). After 1990, although the annual survey still draws on the hukou statistics to design and organise survey, it has added more de facto factors to the survey, including temporary migrants in the currently sampled households. Accordingly, it has increasingly improved its coverage.
In general, the hukou system has played a fundamental role in all population statistics. Although its close link with the population census has been widely appreciated, its interrelationship with other data sources has been less recognised. From any perspective, the effect of the weakened hukou system on other statistics cannot be underestimated. Some of the shortage of births in other statistics can be attributed to this rather than to outright underreporting of births.