Editing Purchasing power parity (section)

===Variations===

There are variations in calculating PPP. The EKS method (developed by Ö. Éltető, P. Köves and B. Szulc) uses the [[geometric mean]] of the exchange rates computed for individual goods.<ref>{{cite web |title=EKS Method |url=https://stats.oecd.org/glossary/detail.asp?ID=5525 |publisher=OECD |access-date=2019-08-26 |archive-date=2019-06-24 |archive-url=https://web.archive.org/web/20190624055426/https://stats.oecd.org/glossary/detail.asp?ID=5525 |url-status=dead }}</ref> The EKS-S method (by Éltető, Köves, Szulc, and Sergeev) uses two different baskets, one for each country, and then averages the result.  While these methods work for 2 countries, the exchange rates may be inconsistent if applied to 3 countries, so further adjustment may be necessary so that the rate from currency A to B times the rate from B to C equals the rate from A to C.