In 2011, the methodology of the Average Earnings Information System (ISPV) was harmonized with the methodology applied in the wage statistics of the Czech Statistical Office (CZSO). The benefit of the harmonisation rests in improved quality of the published wage statistics. Within the harmonisation, the ISPV population was extended by economic subjects not monitored before. The extension of the ISPV population allowed to calculate more accurate numbers above all on employees, and thus since 2011, all ISPV publications has newly stated weighed numbers of employees. Due to the harmonisation, the gross monthly wage median for the wage sphere decreased in 2011. Despite the harmonisation, there are still differences between both surveys due to the specifics of the ISPV survey.
For more detailed information please see http://www.czso.cz/csu/2012edicniplan.nsf/engp/1802-12