Definition: Eltetö-Köves-Szulc-Sergeev method
Purchasing power parities
The Eltetö-Köves-Szulc-Sergeev method (EKS-S method) is a variant of the EKS method (Eltetö-Köves-Szulc method) for calculating PPPs (Purchasing power parities) for basic headings that, under certain circumstances, is better able to handle the asymmetry in the number of representative products priced by countries. With the EKS method, the Fisher type index is calculated as the geometric mean between two PPPs: the PPPs based on products representative in the first country and the PPPs based on products representative in the second country. Products representative in both countries are used for both PPPs. With the EKS-S method, the "Fisher type index" between two countries is calculated as the geometric mean of three PPPs: the PPPs based on products representative in both countries, the PPPs based on products representative in the first country but not the second, and the PPPs based on products representative in the second country but not the first. Symmetry is obtained by giving equal weight in the calculation to the two PPPs that are based on products representative of only one country.
Eurostat, Organization for Economic Cooperation and Development (OECD), "Eurostat-OECD Methodological Manual on Purchasing Power Parities", Publications Office of the European Union, Luxembourg, 2012