In 2007 CentERdata (Tilburg University, the Netherlands) started the MESS project by setting up the LISS panel. The LISS panel is a probability based internet panel representative of the Dutch population, consisting of 5,000 households. On a monthly basis, the panel members fill out questionnaires for about 30 minutes.

With the LISS panel a rich history has already been created of answer-behavior of individual respondents. This yields opportunities to learn about the quality of the data. In one single year more than 70 different questionnaires are fielded and each panel member is selected for an average of 45 questionnaires. In longitudinal (core) questionnaires earlier given answers are preloaded when possible. At the end of each questionnaire the respondent is asked to evaluate the questionnaire on difficulty of answering, understandability of the questions, the pleasure in filling out the questions, the interest in the topic, and whether or not the questionnaire stimulated thinking about the topic.

We will present the first results of a study on answer behavior in the LISS panel. The topics of the study are analysis of the questionnaire duration, evaluation of the questionnaires by the respondents, number of incomplete answered questionnaires, don’t know answers, nondifferentiation behavior in question blocks, consistency checks, and a comparison of answers within households by different members. The study gives insight in relations between the mentioned variables and opens opportunities to distinguish groups on answer behavior as an overture to find modes for improving the meaningfulness of the questionnaires for the respondents and data quality.