EQLS 2012 - Weighting
The EQLS is a random probability survey of people aged 18 and over living in private households. In order to be representative in terms of gender, age, urbanisation level, region and household size, weighting is required for the EQLS.
Selection probability weights, or design weights (w1)
Adults living in households with more adults in them have a smaller probability of being selected for an interview than people living alone. The selection probability weight correcting this is the number of adults in a household. In the EQLS it is maximized at 4.
Some groups of people are more likely to be available or willing to participate in the survey than others. The post-stratification weights correct for undersampling of certain types of populations, by comparing the EQLS to Eurostat data on adult population by age and gender, urbanization and region, and with EU-SILC data on households by household size.
The final national weight is the product of the selection probability weight and the post-stratification weight.
Cross-national population weights
For results representing the whole EU, weights need to be applied to reflect the size of a country’s adult population relative to the EU adult population to correct for underrepresentation of larger countries. These weights include the selection probability weight and the post-stratification weight.
A weighting report on the process was published in 2013.
A revision of the weighting strategy for the EQLS took place in 2014 and a new methodology was developed to calculate post-stratification weights. The results of this research are available in the report Revision of the weighting strategy in the European Quality of Life Survey (EQLS), published in 2015.