The objective of the research is to clarify the key differences between the GDP data published by the World Bank and the IMF (Statista). Based on the differences in data, we make recommendations on how to use the statistics for comparison purposes.
The main difference in the GDP data as published between the World Bank and the IMF is that the former tracks 264 countries whereas the latter covers 194 countries. The calculation of GDP is affected by the use of currency exchange rates and surveys, among other factors.
In general, there are four categories of GDP that are commonly used. They could be based on the price of the current year or a constant price from any previous year. For comparison purposes, GDP could be assessed on a country-by-country basis or based on purchasing power parity (PPP).
PPP converts each country's currency to the US dollar, which indicates the value of goods and/or services that could have been bought in the US, as opposed to converting local currencies using current or historical foreign exchange rates in the market. GDP based on PPP uses a hypothetical international $ for the ease of comparing the purchasing power among different countries.
As to the World Bank (85T) GDP data in 2018, the figures are based on the current price of 2018. For example, the world GDP was $85.91 trillion in 2018. The online database of the World Bank reveals a similar situation: $85.93 trillion and the difference could be due to some form of adjustment after the publication date (December 23, 2019). In comparison, data published by the IMF in October 2019 revealed that the world GDP at the current price was $84.93 trillion.
Data published on Statista ($140T) are statistics sourced from the IMF, which was based on PPP and most current years' prices. For example, the world GDP was $135.76 trillion in 2018. In comparison, data from the World Bank is $128.66 trillion, which was based on the 2018 (current) price, as it is the most recent year's data publicly available.
According to the latest database of the IMF, its October 2019 database covers a similar set of GDP data as those of the World Bank, except without GDP at constant $ prices. The latest April 2020 database by the IMF only made the GDP PPP data available to the public, due to the uncertainty caused by, for example, the COVID-19 global pandemic.
In general, the IMF data has a wide period, ranging from 1980 to 2024, and its 2019 GDP data consisted of partial actual figures, as many countries' information was only estimated as of April 2020. In comparison, the World Bank database gives more variety of the GDP statistics but a narrower time series, ranging between 1990 and 2018.
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