Interviewer Effects on Non-Differentiation and Straightlining in the European Social Survey

In this article we examine the interviewer effects on different aspects of response styles, namely non-differentiation and straightlining, which in general refers to the tendency to provide the same answers to questions in a block of questions. According to research about response styles, the impact of the interviewer on this kind of response behavior is rare. Five blocks of items in the questionnaire in the sixth round of the European Social Survey (2012) are used in the analysis. These data also allow for an evaluation of the differences between countries in terms of non-differentiation and straightlining. Five different measurements of these aspects of response style are used in the analysis. To disentangle the impact of respondents and interviewers on these aspects of response style, a three-level random intercept model is specified. The results clearly show interviewer effects on the respondent’s tendency to select a response category that is the same as the response category for the previous item. In some countries the proportion of explained variance due to differences between interviewers is larger than the proportion of variance explained by the differences between respondents.