Huh:
China’s official demographic figures, including the now-cliched “country of 1.4 billion people”, seriously misrepresent the country’s real population landscape. The real size of China’s population could be 115 million fewer than the official number, putting China behind India in terms of population.
This massive error, equal to the combined populations of the United Kingdom and Spain, is a product of China’s rigged population statistics system, influenced by the vested interests of China’s family planning authority.
China's family planning outfit had an interest in exaggerating population growth. Local schools that lacked kids had an interest in lying about their pupils to get the money for those phantom children. And the state had an interest in believing the school statistics over birth statistics. Also, deaths are under-reported to keep the money spigot going for those old people. Those interests may leave us with 115 million phantom Chinese.
Which has interesting effects on China's long-term chance of having the largest economy in the world, given the reliance on people inputs that have generated much of China's economic rise.
Although China's per capita GDP would be improved with fewer people, of course.
UPDATE: More thoughts on when--or even if--China will surpass America's economic power. The paper rightly criticizes the general application of purchasing power parity to GDP in general. And the paper questions the very theory itself in practice.