Population and housing census is one of the primary sources of data needed for formulating, implementing and monitoring policies and programmes aimed at inclusive socioeconomic development. Over the past decades, methods adopted for the collection of population data have significantly evolved taking advantage of new data sources and technologies.

Thematic Area 1 of the UN World Data Forum 2023 covers exchanges of innovative experience in conducting census. While census technologies have to be based on national contexts, leveraging multiple data sources existing and rapidly developing information technology is a common direction for all. China’s Seventh National Population Census in 2020 involved many innovations in this regard to ensure that everyone was counted despite the challenging conditions under the COVID-19 pandemic. Post enumeration survey reported a net undercount rate of only 0.05%, evidence of success for the innovations adopted.

Here are a few examples of the many firsts in China’s Seventh Census.

Full adoption of electronic data collection for the first time: “EA (enumeration area) demarcation and buildings mapping system” was designed to integrate data from the Government’s departments of natural resources, planning, and civil affairs with data processed using cloud computing. This enabled real-time mapping, editing, reviewing, and reporting across the country at all levels. It took only three months to complete the mapping of boundaries of more than 6 million EAs nationwide, and hundreds of millions of buildings were labeled during the digital mapping process. During the preliminary survey, a nationally unified and standardized electronic household list was established, which linked the household to the building’s and administrative division’s geographic information and laid the groundwork for the future establishment of a geographic information system. Through the development of a census application, data collected on-line were uploaded to the National Bureau of Statistics (NBS) platforms for centralized review and processing. An offline data collection function was developed as well to address the problem of poor Internet connectivity in remote areas, enabling interoperability and verification with online data collection. This largely increased the accuracy and timeliness of the census enumeration, while short form data were collected, reported and pooled into the national dataset in only 15 days.

Online self-enumeration was made available for the first time: Catering to the increasing public awareness on privacy protection, the census application made self-enumeration available through a mini programme built in WeChat, taking advantage of the reach of this mature social media app used in China. A total of over 30 million households opted for self-enumeration.

Including citizens' ID numbers in census for the first time: This is the most noticeable change in the Seventh Census in terms of questionnaire design compared with previous censuses. It allowed for the accurate detection of duplicates and omissions of population and the verification of census data. Specifically, the NBS specified four basic principles while designing the processes for cross-checking and verification: First, ensure all citizen ID numbers are verified and recorded; second, a verified citizen ID number must correspond to a place of usual residence; third, all duplicated citizen ID numbers should be cleaned to correspond to only one place of usual residence; and fourth, for newborns without citizen ID numbers, their place of usual residence should be determined based on the census enumeration information.

Data cross-checking and verification based on administrative records and big data for the first time: This was made available by linking citizen's ID number with administrative records and big data. It also laid a solid foundation for the sharing and use of data between sectoral departments in the future. There were two other important occasions: 1) with support from the State Grid, enumerators were able to check the electricity consumption of each household in the responsible EAs easily and efficiently through a mobile application. This assisted in determining whether a residence was vacant based on information provided by the mobile application, effectively improving the accuracy of the household listing data; 2) Position signal from the telecommunications service providers in China were used to decide the distribution of migrant population.

Online enterprise-type management and training of enumerators and supervisors for the first time: The Seventh Census recruited over 7 million enumerators and supervisors across the country. A management training platform was established using “Internet Plus Technology” to implement an enterprise-type management of the census workforce. Census workers were recruited, trained, and certified using a management model that combined online and offline components. Enumerators had to pass an exam and sign the confidentiality agreement to obtain certification before assuming the position. Besides, in order to standardize the on-site work of enumerators, the NBS developed a behavior analysis function in the data collection system to strengthen supervision of enumerators.

The successful implementation of all these innovations and doing an electronic census approach were attributed to two important factors: 1) the rapid development of information technology and the growing number of Internet users provided solid support for the census' smooth implementation. The Internet and smart terminals have already reached a certain level of popularity, with the Internet penetration rate rapidly increasing from 31.8% during the previous Census in 2010 to 67.0% in 2020, and the number of mobile Internet users increasing from 280 million to 930 million during the same period; and 2) the advancement of computer technologies and infrastructure such as cloud computing and big data provided hosting and technical support for the census. They combine to ensure that the 2020 population census of China was completed successfully during a pandemic, with no COVID-19 infections among the census workers, no delays in implementation, and no geographic areas omitted.

The above China innovations were presented at the UN World Data Forum 2023 parallel session “A New Tomorrow for Population and Housing Censuses? Prospects for the 2030 Census Round and Beyond” (TA1.20), together with the global experiences by UNSD, European experiences from Eurostat and country experiences of Indonesia. It was unsurprising to note the many commonalities of innovations tried out in the 2020 round of census across countries, centering around the increasing use of technologies ranging from mapping, data collection and management and monitoring of field operations to data dissemination, and a bigger role of administrative records. The combination of these approach will lead to a register based census, or a combined modality in the 2030 census round. While each country will develop its own way of such a transition, the WDF has and will continue to provide an important platform of experience sharing and mutual learning, which is very much appreciated.

For more information about innovations in China’s 2020 population census, please visit: https://china.unfpa.org/en/publications/23040301.