To measure job quality, each job is assigned a value, based on the occupational median wages, by linking external information on wages estimated from different data sources. Two external data sources were used to estimate median wages for jobs. It collects information from enterprises with at least ten employees operating in all areas of the economy except public administration (and, in some countries, also the education and health care sectors). At the time of writing, the SES data are available for only two reference years: 2002 and 2006. For sectors not covered by the SES, the median wage is supplemented by data from the European Survey of Income and Living Conditions (EU-SILC).