Does the Inclusion of Non-Internet Households in a Web Panel Reduce Coverage Bias?

The LISS online panel has made extra efforts to recruit and retain households that were not regular users of the Internet into the study. Households were provided with computers and/or Internet when necessary. Including these cases made the panel more representative of the Dutch population, by bringing in respondents who were more likely to be older, to live in single-person homes, and to have migration backgrounds. This article replicates five published articles that used LISS data and explores how the conclusions in these articles would have been different had the LISS panel not included the non-Internet households. There are strong demographic differences between the Internet and non-Internet households, and estimates of means would in many cases be biased if these households had not been included. However, across the five replicated studies, few of the published model estimates are substantively affected by the inclusion of these households in the LISS sample.