Purchasing power parities
The second step of validation: investigating the possible errors detected during the editing of survey prices to establish whether or not they are actual errors and, if they are actual errors, correcting of suppressing them. In many cases, verification will require revisiting the outlets where the prices were collected to see whether what was priced matches the product description and whether the correct price and quantity were recorded. Price observations that are found to be incorrect should be either eliminated or replaced by the correct observation.
Eurostat, Organization for Economic Cooperation and Development (OECD), "Eurostat-OECD Methodological Manual on Purchasing Power Parities", Publications Office of the European Union, Luxembourg, 2012