In this paper we discuss a three-step strategy to evaluate data quality in terms of item nonresponse and to identify potentially flawed questions. We provide an example with several data sets of a large-scale social scientific study to illustrate the application of the strategy and to highlight its benefits. In survey research it is common practice to test questions ex ante, for example by means of cognitive pretesting. Nevertheless, it is necessary to check the respondents’ response behavior throughout the questionnaire to evaluate the quality of the collected data. Articles addressing item nonresponse mostly focus on individuals or specific questions …