The World Bank reported that China may surpass the U.S. as having the largest economy in the world this year, estimates a new report by the World Bank's International Comparison Program. The United States of America has consistently remained as the world's largest economy since 1872.

Other recent studies have suggested that this change will not happen until 2019, but the exact date is impossible to know due to limitations on data collection, reported rt.com. Since the 2008 financial crisis, the U.S. economy has contributed about 7.6 percent of the world's total economic growth, whereas China's economy has contributed roughly a quarter of it. (The International Monetary Fund predicted that the economy of China accounts for 24 percent of economic growth during the 2011-2014 period.)

Purchasing power parity is used to get the recent estimates, which is more accurate than merely comparing the nominal values involved. Whereas nominal value would simply compare the exact amounts of currency involved, purchasing power parity adjusts based on what goods and services could be had for that amount of currency in each of the places being compared. The Wall Street Journal said that the index tries to evaluate the economy size, which is based on the belief that non-tradable goods and services in poorer countries do not cost as much in real terms and may not have as much real worth. For example, goods produced in China do not cost as much money, and due to more lax consumer protection regulations, may not last as long or be as safe as one produced in the United States. Depending on the size of these separate discrepancies, the product may ultimately be more or less expensive, and attempting to compensate for that is at least as much art as science for economists.

The accessibility of trustworthy data is also a problem in measuring the real size of China's economy. China's secretive and authoritarian government is not committed to open information and has been known to alter economic data for political reasons. Even if it were being as forthright as possible with its numbers, its economy also features unlawful and unreported shadow revenue sourced from bribery, sex-based commerce, and several unlawful types of merchants that are not included in official figures, which could potentially distort the true numbers significantly.

Of course, sheer size of the economy is not the only important measure of how well the nation is doing economically and how powerful it is. The nation's standard of living, for example, measures how well each Chinese citizen is doing on average. On this important measure, China fares more poorly than many developing nations. In terms of per capita purchasing power parity, the economy of China was listed 93, which was a little above Albania and Turkmenistan but is far behind Libya, Surinam and Azerbaijan. Advancing beyond this low rank will take China a long time.