Rotation group bias in European Union social indicators

As EU-SILC relies on a four-wave rotational panel design, a new population sample is drawn every year and selected respondents are interviewed annually for up to 4 years. This means that a complete EU-SILC cross-sectional data set contains data from samples drawn independently in 4 different years. In Chapter 17, Alessio Fusco, Giovanni Gallo and Philippe Van Kerm apply influence function (IF) regression methods to examine to what extent this design has an impact on the estimates of four EU social indicators (the AROPE AROP indicators, the MSD indicators, introduced above, and the Gini coefficient (7)), in other words if a rotation group bias in these indicators is observed. Their analysis highlights that estimates of income inequality and poverty rates for newer rotation groups are often higher than for older ones. Individuals interviewed at least twice (and especially those who have been in the sample for 3 or more years) tend to drag the selected social indicators downwards, compared with individuals interviewed for the first time. These impacts remain significant even when accounting for observable sociodemographic characteristics of households; not all countries are affected by the bias, however.