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 behaviors and other topics prone to socially desirable responding. This paper defines interviewer effects, argues for the importance of measuring and controlling for interviewer effects in health surveys, provides advice about how to interpret research on interviewer effects and summarizes research to date on race, ethnicity and gender effects. Interviewer effects appear to be most likely to occur when survey items query attitudes about sociodemographic characteristics or respondents' engagement in sensitive behaviors such as substance use. However, there is surprisingly little evidence to indicate whether sociodemographic interviewer-respondent matching improves survey response rates or data validity, and the use of a matched design introduces possible measurement bias across studies. Additional research is needed to elucidate many issues, including the influence of interviewers' sociodemographic characteristics on health-related topics, the role of within-group interviewer variability on survey data and the simultaneous impact of multiple interviewer characteristics. The findings of such research would provide much-needed guidance to public health professionals on whether or not to match interviewers and respondents on key sociodemographic characteristics.