Note: Over GDP, 1 US dollar (US$) = 1 international dollar (I$). Purchasing power parity is the number of currency units required to buy goods equivalent to what can be bought with one unit of the base country. We calculated our PPP over GDP. That is, our PPP is the national currency value of GDP divided by the real value of GDP in international dollars. International dollar has the same purchasing power over total U.S. GDP as the U.S. dollar in a given base year.
For more information and proper citation see http://www.rug.nl/research/ggdc/data/pwt/pwt-7.1
Source Indicator: ppp
Source: University of Pennsylvania
Release: Penn World Table 7.1
University of Pennsylvania, Purchasing Power Parity over GDP for El Salvador [PPPTTLSVA618NUPN], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/PPPTTLSVA618NUPN, February 13, 2016.