The National Bureau of Statistics (NBS) announced on March 8 adjustments to the decade-old method it uses to measure China's production and investment.

Beginning January this year, China had revised the statistical threshold of "large" industrial enterprises to an annual business income above 20 million yuan ($3.04 million), from the previous 5 million yuan ($761,000), when compiling industrial production data, the NBS said in a statement on its website.

Enterprises that are above the new criteria would be surveyed one by one, while under-criteria companies would be calculated by sample surveys, according to the NBS.

For fixed assets investment data, the threshold was raised to 5 million yuan, up from the previous 500,000 yuan ($76,100), while bringing projects in rural areas into the statistical count, the NBS said.

The NBS had used the old statistical method since 1998 when China's GDP was only 7.9748 trillion yuan ($1.21 trillion at current exchange rate), compared with 39.8 trillion yuan ($6.05 trillion) in 2010.