This document gives an overview of the methods and sources used to create version 25 of Gapminder’s estimates of GDP per capita for all countries from 1800 to 2040.
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In order to make economic levels of all countries comparable over time, despite all the differences in currencies, inflation and prices, we have aligned all other sources to this World Bank indicator which we currently use as our gold standard: GDP per capita, PPP (constant 2011 international $)
- Years: 1990 to 2016: We use the World Bank data whenever available. A few countries were missing and we have made our own estimates, most notably for Syria (see special cases below).
- Years before 1990: We base our estimates on data from economic history researchers from across the world, compiled by the Maddison project. those numbers are expressed in PPP 2015 and we have converted them to PPP 2011 which is the updated currency used by the World Bank. We linked each countries historic series to hit the first available datapoint from the World Bank. But a simple currency conversion across the total time-frame since 1800, would move all countries relative to each other based on their price levels in 2011, which would distort the historic picture completely. To avoid that we made sure we keep the historic picture in the Madison data. After aligning the end of the series to PPP 2011, we adjust every countries growth rate every year between 1900 and 1990, so that the countries relative positions prior to 1900 are maintained. IN addition to that we also adjusted all growth rates to make sure we maintain Maddison’s total global growth rate over the complete period 1820 to 2000. We also filled all gaps and added our own estimates for countries that were completely missing in the Maddison data, which is documented here.
- Years: 2017 to 2022: we extend the World Bank data with forecasts from IMF World Economic Outlook. Where IMF has not forecast we have just extended our series with the growth rates of the latest available years.
- Years: 2023 to 2040: Sometimes we show graphs with income estimates beyond 2022. We don’t believe anyone can predict the economic future of the world. Those are guesstimates should only be used to show what the world will look like if economic growth continues roughly at the current speed. Some countries have extremely high or low growth rates in the IMF forecasts. If we just extended those we would see them reach extremely unlikely economic levels in 2040. To avoid that we smoothly move all countries’ growth rates to a common global growth rate over the period of 2022 to 2030
Syria has no official GDP per capita estimate since 2010. A preliminary documentation of how we estimated it is available here, based on this paper:
Jeanne Gobat ; Kristina Kostial IMF working paper on Syria Page 10, Table 2 in A IMf-working paper on Syria estimates the Real GDP and Composition (In billion 2000 Syrian pounds) Est. Table 2. Syrian Arab Republic: Real GDP and Composition (In billion 2000 Syrian pounds) Est. Downloaded File wp16123.pdf on October 9 2017 from https://www.imf.org/en/Publications/WP/Issues/2016/12/31/Syrias-Conflict-Economy-44033