Calibrating Questionnaires with Weekly Diaries : An Application in Religious Behavior, Netherlands 1975 to 2005

This article presents an innovative approach to improve the power of questionnaires by combining them with weekly diaries. The aim is to show how one can calibrate information collected from questionnaires, which provide a distribution that is in general biased, with diary data, which are more accurate but cannot provide a distribution across a range of frequencies. These problems become even more pronounced when the object of analysis is a specific issue, such as religious practice, the focus of this study. The suggested user-friendly model uses the more accurate diary data to adjust the distribution produced by the standard questions and enables researchers to obviate the problems of the two data collection methods. To present a practical application, the Time Budget Survey, conducted at five-year intervals between 1975 and 2005 in the Netherlands, is used.