The mainland is considering a centralised and unified accounting system for calculating the size of its economy amid concerns over the reliability of the data. Peng Zhilong, chief of the accounting department with the National Bureau of Statistics, wrote in a People's Daily article that the credibility of the system had been hurt by systematic double counting, incoherent accounting standards and deliberate manipulation at a local level. Mismatches in nationwide and provincial gross domestic product and retail figures prompted debate over whether the world's third largest economy was genuinely on the road to recovery. One repeatedly challenged issue is the gap between the national GDP figure released by the bureau and the sum of the GDP figures submitted by the 32 provincial-level governments. The national figure was 13.99 trillion yuan (HK$15.85 trillion), nearly 1.4 trillion lower than the provincial total of 15.38 trillion yuan. The disparity, a regular occurrence, was inevitable under the current mechanism of data collecting and processing, Mr Peng wrote. 'We also can't rule out the possibility of officials inflating figures as it [GDP growth] is tied to their promotion.' Lower-level statistics agencies are held accountable to local governments rather than the national body and follow local rules of data collection. Mr Peng said his agency was pushing for change. 'First, we will unify the rules in counting the size of provincial economies ... and, second, we will facilitate more enterprises to submit their data to the central government directly, cutting out the processing in between,' said Mr Peng, who also threatened punishment for those who manipulated data. The bureau has long been under fire for dubious economic statistics, and traditionally its statisticians have kept a low profile. But since the economic downturn added increased political significance to GDP data, the bureau has begun to publicly defend the integrity of its work. Liu Yuanchun, deputy head of the economics school at Renmin University, said centralisation was the right step, but people should not hold their breath. 'The whole statistics collection system is problem-ridden, but it's an issue playing way out of the hands of the NBS,' Dr Liu said. 'It requires an overhaul of the way politics operates in China.' Andy Xie, the Shanghai-based former Morgan Stanley chief Asian economist, said transparency was the key issue. 'It [the GDP data debate] has turned into a wider government credibility issue,' he added.