Factbox: What's new in China's 2020 population survey versus 2010 census

BEIJING (Reuters) - More than 1 billion Chinese citizens will participate in a once-in-a-decade census that will inform policymakers on demographic shifts in the world's most-populous but fast-ageing nation, and help shape social and economic policies in the years to come.

Over 7 million census takers began going door to door on Sunday to collect information ranging from car ownership to whether they have family members in Hong Kong or Taiwan. Authorities will publish the survey results in April.

Below are some changes in the way the census is being conducted compared with the 2010 survey, to reflect a wealthier and older population:

LONGER SURVEY

Census takers, instead of pen and paper, are armed with smartphones and computer tablets. While that may increase the accuracy of data collection, it does not shorten the survey window, which will last more than a month, ending on Dec. 10. The 2010 census took only 10 days.

The number of questions have increased to 19 from 18 previously. Also, 10% of the population will be selected afterwards to answer 48 questions in a second questionnaire, compared with 45 previously.

IDENTITY CARD NUMBER

Identity card numbers are logged for the first time, electronically linking the information collected to identifiable individuals. Officials have said the ID card details are to be matched with data recorded by the police and health services and other authorities to ensure accuracy. They pledged that the information will be kept strictly confidential, and will not be used for any other purpose beyond the survey.

HONG KONG & TAIWAN

For the first time, survey respondents must disclose the number of family members who are residents in Hong Kong, Macau and Taiwan, or are now foreign nationals. No other details on those family members are being asked.

RISING RENTS

In the longer questionnaire, respondents are asked to indicate the amount of rent they pay each month. The top bracket is "10,000 yuan or higher" ($1,495). That's much higher than the highest tier of "3,000 yuan or higher" in the 2010 census, reflecting the sharp increase in property values in the past decade in China and the higher cost of living.

CAR OWNERSHIP

Also in the second questionnaire, respondents are asked for the first time to indicate if they own cars. They are to additionally disclose the overall value of all the cars they own, pointing to the increased private wealth created in the past 10 years. No other assets, such as the number of properties owned, are required to be divulged.

LAND RIGHTS

In the past, respondents were asked if they hold urban or rural residency permits under a decades-old "hukou" household registration system. In this year's census, respondents are simply asked if they hold management rights to rural land, reflecting Beijing's renewed focus on rural land resources and their utilisation. All rural land is owned by local collectives, not the state. Farmers have the right to use land owned by their local collective under long-term contracts, and can lease out the management of their land to others if they wish.

THE AGED

In the 2010 census, citizens aged 60 and above were asked to describe their general health. For the first time, this year, they are additionally asked about their living situation - whether they are living alone, with a partner, with their children or in an institution. China is facing what experts call a "demographic time-bomb", following a decades-long one-child policy, which was finally abandoned in 2016. In 2018, almost a fifth of Chinese citizens were aged 60 and over, or 249 million people.

(Reporting by Ryan Woo and Liangping Gao; Editing by Stephen Coates)