Socio-demographic characteristics of interviewers have a potential biasing effect on data quality. Among others race/ethnicity and gender are the most prominent characteristics analyzed in the literature. Evidence from the literature suggest, that sensitive items – especially questions on gender-related topics – evoke gender-of-interviewer effects. Sometime effects are predominant in opposite gender settings where interviewers of one sex administer a survey to a respondent of the opposite sex, sometime scholars observe reverse interrelations. So far it remains unclear whether these effect occur because respondents are prone to measurement error on the reporting stage (social desirability) or whether the gender or the interviewer modifies the perceived question meaning.

In recent years, Web surveys have become a standard survey mode. So far, online questionnaires resemble their paper counterparts to a great extend: online measurement instruments rely mostly on visually presented written questions with associated response categories. However, compared to paper and pencil questionnaires Web surveys allow for more rich communication with the respondent: graphical elements, pictures, and animated GIFs are used to enhance the appearance of web pages. As a result some Web surveys make use of a humanized interface, e. g. a picture of the investigator, pictures of people performing activities that the respondents are supposed to report on and the like. Earlier studies could demonstrate that those low-intensity humanizing elements have no or only marginal effects on the responses obtained.

However, with the wide spread availability of broadband Internet connections video and/or audio are being used in Web surveys as well. Accordingly, in this study we will assess the impact of pre-recorded video clips of interviewers reading the questions to the respondents. This should enhance the social presence of a human in the survey situation, which in turn should induce more pronounced reactions from the respondents in response to theses humanizing factors.

The paper reports results from a field-experimental study on the impact of video support in Web surveys on data quality. Within a Web survey among university students a standard interactive online questionnaire was used. A random sub-sample answered a version of the questionnaire that consists not only of written questions but also of corresponding video files of interviewers reading the questions to the respondent. 800 respondents were randomly assigned to either of three versions: (1) a traditional text-based version of the questionnaire, (2) a video-enhanced version using a female interviewer and (3) a video-enhanced version using a male interviewer. The survey covered a variety of questions on relationships and sexual behaviors including several highly sensitive items on sexual practices, sexually transmitted diseases and the like.

In the presentation we will assess the impact of the gender of the interviewer (in relation to the gender of the respondent) on standard data quality indicators: item non-response, social desirability, over- and underreporting. Preliminary finding suggest, that the video in itself does not affect data quality negatively. However, for highly sensitive questions and topics that relate to the self-presentation of the respondents in front of an opposite-gender interviewer, gender of-interviewer effects are to be observed.