Patterns of nonresponse for key questions in NSDUH and implications for imputation
Frechtel, P., & Copello, E. (2007). Patterns of nonresponse for key questions in NSDUH and implications for imputation. In Proceedings of the Survey Research Methods Section, American Statistical Association (pp. 2457-3464) http://www.amstat.org/sections/srms/proceedings/y2007/Files/JSM2007-000795.pdf
The idea of using "soft nonrespondents" to represent "hard nonrespondents" is not new to survey research. Callbacks are often used to adjust for nonresponse in surveys. The goal is to control nonresponse bias by assuming that the hard nonrespondents are more similar to the callback respondents than they are to the original respondents.
The National Survey on Drug Use and Health (NSDUH), an annual nationwide survey involving approximately 70,000 subjects per year, does not make use of callbacks. However, for several key questions in the NSDUH, follow-up questions, or “probes,” are presented to subjects who entered a response of “don’t know” or “refused” to the original questions. The probes are intended to increase item response rates by simulating an actual interviewer. The probe respondents can be considered soft nonrespondents, and the subjects that answer neither the original question nor the probe can be viewed as hard nonrespondents.