Recent methodological studies have attempted to decompose the interviewer variance introduced in interviewer-administered surveys into its potential sources, using the Total Survey Error framework. These studies have informed the literature on interviewer effects by acknowledging interviewers’ dual roles as recruiters and data collectors, thus examining the relative contributions of nonresponse error variance and measurement error variance among interviewers to total interviewer variance. However, this breakdown may depend on the interviewing technique: some techniques emphasize behaviors designed to reduce variation in the answers collected by interviewers more so than other techniques. The question of whether the contributions of these error sources to total interviewer variance change for different interviewing techniques remains unanswered. Addressing this gap in knowledge has important implications for interviewing practice because the technique used could alter the relative contributions of variance in these error sources to total interviewer variance. This article presents results from an experimental study mounted in Germany that was designed to answer this question about two specific interviewing techniques. A national sample of employed individuals was first selected from a database of official administrative records, then randomly assigned to interviewers who themselves were randomized to conduct either conversational interviewing (CI) or standardized interviewing (SI), and finally measured face-to-face on a variety of cognitively challenging survey questions with official values also available for verifying the accuracy of responses. We find that although nonresponse error variance does exist among interviewers for selected measures (especially respondent age in the CI group), measurement error variance tends to be the more important source of total interviewer variance, regardless of whether interviewers are using CI or SI.
