How Are Residents' Incomes Calculated?

Recently, a piece of good news delighted the people of Zhejiang: in 2014, the per capita disposable income of all residents in Zhejiang was 32,658 yuan, ranking third among the country's 31 provinces (autonomous regions and municipalities) and first among the provinces (autonomous regions). Moreover, farmers' incomes in every county of Zhejiang exceeded 10,000 yuan, with last year's per capita figure approaching 20,000 yuan.

However, some netizens did the math on their own household budgets and raised questions: "My income didn't really rise this year. How is this income figure calculated? Have I been averaged out again?" A reporter interviewed the relevant statistical experts from the Zhejiang Survey Office of the National Bureau of Statistics.

Income of the whole population obtained through sampling

Every quarter, the Zhejiang Survey Office of the National Bureau of Statistics publishes the income situation of Zhejiang residents to the public. From these data, you can see what level Zhejiang people's incomes are at, and you can also work out whether your own income has driven growth or held it back.

Residents' income and expenditure data are collected in accordance with the integrated urban-rural household income and expenditure survey system formulated by the National Bureau of Statistics, adopting nationally unified sampling methods, survey indicators, survey methods, data processing and data release principles.

A total of 2,300 survey communities were selected across the province, with 23,000 survey households distributed across all 32 districts, 36 counties and 22 county-level cities in the province, averaging 256 households per county (city, district). These survey households cover the province's cities and townships, and also include the non-local population permanently residing in the province. These survey households record their income and expenditure every day, and each household's survey data is reported to the Zhejiang Survey Office of the National Bureau of Statistics, and finally statistically aggregated to obtain the per capita disposable income of all residents, urban permanent residents and rural permanent residents in the province.

Data comes from diary accounts

Because the number of households in the province is very large, it is impossible to obtain the province's resident income data by surveying the income of every household, so the sampling survey method is usually used to select some resident households as accounting households. The statistical experts told us that each survey household is determined through a strict sampling procedure, and it is absolutely not a matter of casually finding some households to carry it out.

The sampling survey method is a statistical survey method commonly used internationally. It takes statistical probability theory as its theoretical basis. Through a scientifically designed and rigorously operated sampling procedure, survey households are randomly selected, avoiding any subjective choice of survey households, and the overall population is inferred from the sample data. Just as in product quality inspection, some products are selected through random sampling to obtain the product quality qualification rate, thereby determining the quality qualification status of that batch of products.

The 23,000 urban and rural resident households selected across the province must record the income and consumption situation of all permanent household members every day. Each survey community hires an assistant surveyor, and the province's 2,300 assistant surveyors provide accounting guidance to the survey households, check the quality of the accounting, distribute and collect the account books, review and code each record of the survey households, and then send them to the county-level statistical survey departments for data review, entry, aggregation and reporting, ultimately obtaining the per capita disposable income of all residents, urban permanent residents and rural permanent residents in the province and each region.

Survey data is scientific and credible

In March 2014, our province released province-wide integrated urban-rural income data for the first time: in 2013, the per capita disposable income data of all residents in our province was 29,775 yuan. Per capita disposable income is an average figure, obtained by averaging the incomes of households with different incomes. In reality, at least more than half of households fail to reach this income average.

Before this, our province's per capita income data, like the national data, was at the stage of "urban-rural dualism," released as two types of data: "per capita disposable income of urban residents" and "per capita net income of rural residents."

Compared with the previous urban-rural divided household survey, the integrated household survey has many advantages: for example, the indicator settings are more complete, and the survey scope is fully covered. The sampling frame of the integrated household survey was compiled using the data of the Sixth National Population Census, strengthening the coverage of the floating population and the population in urban-rural fringe areas, achieving no duplication and no omission in sampling, with complete coverage.

The survey subjects have also been made permanent-resident based. In particular, for migrant workers whose homes are in rural areas but who go out all year round, their income and expenditure situation is now investigated directly with them at their place of permanent residence, instead of with their family members at their rural household registration place as before, in order to reduce underreporting. At the same time, the survey content is richer and the sampling method is more scientific. At a 95% confidence level, the sampling error of the national per capita disposable income of residents is less than 1%, and the sampling error of the province's per capita disposable income of residents is less than 3%.

Of course, with the increase in urban and rural residents' incomes, the strengthening of privacy protection awareness and the increase in population mobility, the accounting work of household surveys is becoming more and more difficult. For this reason, statistical survey departments need to regularly visit accounting households, strengthen the building of the assistant surveyor team, establish strict and standardized quality control systems for stages such as sample rotation, data collection, data processing and data release, eliminate various interferences, and ensure the quality of residents' income and expenditure data.