An Evaluation study of the Event History Calender

To obtain valid and reliable data in survey interviews, it is generally acknowledged that the interviewer's behavior should be standardized in order to provide each respondent with the same stimulus and prevent the interviewer affecting the answers of the respondent (Fowler & Mangione, 1990). Conducting an interview using an event history calendar (EHC), however, usually requires the interviewer to be much more flexible. Although completely structured interviews with an EHC have been done (Furstenberg, Brooks-Gunn, & Morgan, 1987), the more common approach is to use a semistructured format with an initial prescribed question for each (sub)domain (Freedman, Thornton, Camburn, Alwin, & Young-DeMarco, 1988). In such an approach, the interviewer is required to react to the respondent's answers, which in turn may produce unwanted interviewer variance and thus may endanger the quality of the data. Thus, interviewers on the one hand have to pose the questions as worded in the questionnaire, but on the other hand have to probe, for example asking whether a particular situation has changed, using their own words and based on their own judgment given the answers of the respondent. The flexible approach is especially expected to improve data quality with regard to resolving inconsistencies and checking the respondent's memory (Belli, Shay, & Stafford, 2001). However, such freedom may cause the interviewer also to perform nonstandardized behavior in cases where standardized behavior may have been more appropriate (e.g., using suggestive probes; see Smit, Dijkstra, & Van der Zouwen, 1997). Moreover, administering an EHC is quite a complex task. Interviewers have to grasp the essential ideas underlying the EHC method and apply techniques like parallel probing in an adequate way, whereas filling in the calendar itself is much less straightforward than filling in a usual questionnaire from a survey interview. In this chapter we present two studies in the context of a large tobacco epidemiology study evaluating interviewer performance in administering an EHC. The first study concerns a paper-and-pencil version of the EHC; the second one a computer-assisted version. First we describe the underlying principles of the EHC and the task of the interviewer in more detail.