Evaluation of follow-up probes to reduce item nonresponse in NSDUH
Technological advances in survey research over the past 15 years offer the ability to improve the quality of face-to-face survey data in part by reducing item nonresponse. Assuming the instrument has been programmed correctly, computer-assisted interviewing (CAI) can eliminate missing data caused by confusing skip instructions, hard-to-locate answer spaces, and simple inattention to the task at hand. Yet in and of itself, CAI cannot reduce the item nonresponse created when a respondent chooses to give a "Don't know" or "Refused" response to a survey question. Previous research (see, e.g., Turner, Lessler, & Gfroerer, 1992) has shown that these types of responses are more common in self-administered questionnaires than in those administered by an interviewer. Most likely, this occurs because in a self-administered interview the interviewer does not see the respondent's answer and thus cannot probe or follow up on these types of incomplete responses. This chapter introduces a methodology designed to reduce item nonresponse to critical items in the audio computer-assisted self-interviewing (ACASI) portion of the questionnaire used in the National Survey on Drug Use and Health (NSDUH).1 Respondents providing "Don't know" or "Refused" responses to items designated as essential to the study's objectives received tailored follow-up questions designed to simulate interviewer probes.