Can We Make Official Statistics with Self-Selection Web Surveys?

At first sight, web surveys seem to be an interesting and attractive means of data collection. They provide simple, cheap and fast access to a large group of people. However, web surveys also suffer from methodological problems. Outcomes of web surveys may be severally biased, particularly if self-selection of respondents is applied instead of proper probability sampling. Under-coverage is also a serious problem. This raises the question whether web surveys can be used for data collection in official statistics. This paper addresses the problems under-coverage and self-selection in web surveys, and attempts to describe how Internet data collection can be incorporated in normal data collection practices of official statistics.