It is all change at the top of the world economy power league. Not since the late 19th century, when the US overtook the UK as the world’s largest economy, has there been a re-ranking this significant. The International Monetary Fund and World Bank annual meetings this October mark roughly the moment that China will become the world’s largest economy.

Although the reinstatement of China as economic top dog has been forecast for years, we have leading statistical agencies to thank for bringing forward the date, now likely to be 2014 rather than some time in the 2020s. In April, they found that a typical Chinese citizen could buy more goods and services with one renminbi than previously thought.

Coming together under the International Comparison Program (ICP), hosted by the World Bank, these statisticians announced new conversion factors – purchasing power parity indicators – to estimate what money can buy in different countries.