Internet Coverage Bias in Web Surveys in Europe

The use of web surveys has increased over the last decades in an attempt to reduce survey costs and maximise response rates; this trend has accelerated during the Covid-19 pandemic, when social distancing measures impede face-to-face data collection. Despite the widespread use of web surveys, the uncomplete Internet coverage may still pose a threat to data quality. Using large scale probability-based Eurobarometer data from 2010-2019 we: i) describe the trend in Internet coverage rate across Europe, ii) investigate demographic and socio-economic differences between the Internet and non-Internet population, iii) explore variation over time and across countries in Internet coverage bias, and iv) assess whether countries' socio-economic context is associated with Internet coverage bias. We find that a non-negligible share of the population does not use the Internet and Internet coverage varies widely across Europe. In addition, we document that coverage bias: decreases over time for most of the variables considered; seems more pronounced in age, education, and life satisfaction, and negligible in other variables; and is associated with countries' socio-economic context.