Interviewer effects in public health surveys

Interviewer effects can have a substantial impact on survey data and may be particularly operant in public health surveys, where respondents are likely to be queried about racial attitudes, sensitive behaviours, and other topics prone to socially desirable responding. This paper defines interviewer effects, argues for the importance of measuring and controlling for them in health surveys, provides advice about how to interpret research on interviewer effects, and summarises research to date on race, ethnicity and gender effects. Interviewer effects appear most likely to occur when survey items query attitudes about socio-demographic characteristics or respondents’ engagement in sensitive behaviours such as substance use. There is little evidence on whether socio-demographic interviewer–respondent matching improves survey response rates or data validity and whether the use of a matched design introduces possible measurement bias across studies. Additional research is needed on the influence of interviewers’ socio-demographic characteristics on health-related topics, the role of within-group interviewer variability on survey data, and the simultaneous impact of multiple interviewer characteristics.