probability sample, or it may be caused by self-selection in an internet survey. A contraction theorem from mathematical …

not use the internet. We run a large-scale opinion survey with (1) onliners in web mode, (2) offliners in face … sampling differences. In our setting, re-weighting online-survey observations appears a pragmatic solution when aiming at …

business survey in the German business-related services sector when respondents may freely choose to respond either online or …