BEIJING -- China's top statistics agency, the National Bureau of Statistics (NBS), offered an explanation on Thursday for a residential housing figure that confused the public.

A detailed explanation by Xian Zude, the NBS's chief statistician, was published on the bureau's website after the public voiced distrust and confusion in regard to a housing figure used by the NBS to calculate the cost of living for Chinese citizens last year.

The NBS said in a report last week that residents on the Chinese mainland spent an average of 111 yuan ($17.1) per month on housing in 2010.

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Xian said the figure was a "narrow measurement" that only included utility fees, rent and building management costs, and did not account for mortgage amortizations for home purchases.

The figure was lower than the report's other figures, which stated that Chinese citizens spent an average of 400 yuan on food, 165 yuan on transport and telecommunications, 136 yuan on education and entertainment and 120 yuan on clothing in 2010, according to the NBS.

"The public and several statisticians do not properly understand the source of the misleading data, nor do they know to what scope the figure can be applied," Xian said.

To use a broader measure of living costs in China's urban areas, the average amount spent on housing by urban residents was 636 yuan per month in 2009, Xian said.

Zheng Xuegong, the NBS official responsible for releasing the misleading figure, apologized for the confusion on Wednesday, saying that the figure should be adjusted to over 636 yuan on the basis of gross domestic product (GDP) growth.

The NBS will publish more housing statistics next Wednesday, according to Xian, adding that the statistics will include urban housing costs derived from a nationwide survey of 65,000 households.

China registered more than 401 million households as of Nov 1 last year, according to data from the country's most recent national census.