EU-SILC a jeho metodologická úskalí: mezinárodní srovnatelnost a příjmové proměnné [EU-SILC and its Methodological Pitfalls: International Comparability and Income Variables]

The European Union Statistics on Income and Living Conditions (EU-SILC) set of surveys are an important source of comparative statistical data. EU-SILC provides data on income, living conditions, poverty and social exclusion, material deprivation: topics of growing interest to scholars in Europe and elsewhere. EU-SILC surveys are fielded in 29 European countries and coordinated by Eurostat. Although the survey is harmonised, the individual level microdata consists of many dissimilarities across participating countries because of different national conditions, methods of data collection and/or data processing. The aim of this article is to discuss the opportunities and limitations of EU-SILC datasets. In addition to discussing the development, methodology and basic pitfalls of EU-SILC, this article focuses on (a) income variables, (b) differences in income among countries and (c) impact of income differentials on data comparability. The main problems of income data may be summarised as follows. 1) Some countries use registers to report income variables while others obtain this information from interviews, and this difference lowers their comparability. 2) The incidence of negative or zero values makes the construction of poverty and inequality measures difficult. 3) There are national differences in the net-to-gross income conversion procedure. This study shows using a four country analysis that the net-to-gross conversion procedure overestimates gross wages in two countries and underestimates it in two others. Notwithstanding these methodological issues, EU-SILC is an important resource for the comparative study of income.