China’s economic growth unexpectedly accelerated in the third quarter, according to the estimates of analysts polled by The Wall Street Journal, a finding that runs counter to official statistics and could help explain the central bank’s recent move to raise interest rates.

The poll, the latest in a quarterly series, asks economists for their estimates of China’s growth in the same seasonally adjusted quarter-to-quarter terms used by other major economies. China officially reports changes in gross domestic product only relative to the same period a year earlier, which can make it harder to discern turning points in the economy.

The National Bureau of Statistics reported last month that the country’s gross domestic product was 9.6% higher than a year earlier in the third quarter, slowing from the 10.3% expansion in the second quarter. The figure was in line with market expectations and consistent with the government’s public statements that it has been gradually cooling down the economy to avoid risks from the huge stimulus plan launched in late 2008.

But a closer examination of the figures paints a more complex picture. According to the median estimate of the 12 economists surveyed, China’s GDP for the third quarter expanded 9% from the previous quarter on an annualized, seasonally adjusted basis, actually picking up from an estimated 8.2% growth in the second quarter. In the Journal’s previous poll in August, economists had forecast third-quarter growth to slow to 7.9%.

Explanations for the rebound vary: purchasing managers’ index surveys appear to show Chinese manufacturers rebuilding their inventories since August, after running down stocks for several months. Policy may also have been more supportive of the economy than rhetoric suggested: the government budget swung to a deficit in the third quarter from a surplus in the previous quarter, which would help boost growth, and new bank lending was steady in the quarter .

Still, most economists also seem to think the rebound in the third quarter is a blip in a downward trend: their expectations still center on China’s growth rate settling in around 9% next year, after the double-digit expansion in early 2009 as the government’s stimulus plan took effect. The median forecast for the last quarter of this year is for growth of 8.7%.

China’s central bank, which makes its own estimates of seasonally adjusted growth rates, also seems to agree with private-sector economists. In a report at the end of October, the People’s Bank of China said: “After seasonal adjustment, the sequential annualized growth rate for third-quarter GDP was slightly higher than the previous quarter.” The central bank didn’t give a figure for its estimate.

The response was clear enough: The central bank raised benchmark interest rates on Oct. 19 for the first time in nearly three years. The central bank later said the move was aimed at containing expectations of inflation and a frothy property market, and that it plans to continue to gradually “normalize” monetary policy from the extremely loose settings adopted during the crisis.

Participating in the Journal’s poll were economists on the staff of Bank of America-Merrill Lynch, Capital Economics, China International Capital Corp., Citigroup, Deutsche Bank, JP Morgan Chase, Morgan Stanley, the Organization for Economic Cooperation and Development, Royal Bank of Scotland, Standard Chartered and UBS, as well as the independent economist Albert Keidel.