What is interviewer bias?

Date of publication: June 15, 1969


There has been some misplaced mistrust of surveys of attitudes on the grounds that responses to attitude questions show more bias than responses on matters of fact (such as product usage and demographics). It has been suggested that one such source of bias could be interviewers consciously or unconsciously projecting their own attitudes to the topics being discussed onto their respondents. This paper examines this hypothesis in the light of the total context of interviewer bias. It examines a specific survey carried out in Britain in which 100 interviewers conducted 1,730 interviews using a lengthy questionnaire which covered a variety of usage, attitude and demographic data relating to the confectionery market. As a matter of routine quantity control checking, selected results are analysed by interviewer; and as an addition in this case, each interviewer completed the full questionnaire at the briefing session, ostensibly as a training exercise. Half of the interviews were self-completed and the rest were face-to-face interviews. These interviewer questionnaires have now been analysed and compared with the results obtained by the actual survey sample. Additionally each interviewer's results have been related to those of the people they interviewed and the variations and relationships studied in relation to a number of interviewer variables such as age, experience, personality, geographic area, and also to the interviewer's own attitudes to the subject of the survey.

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