The unable to participate survey disposition is used in all types of surveys, regardless of mode. It occurs when the selected respondent for a survey is incapable of completing the telephone or in-person interview or of completing and returning the Web-based or mail questionnaire. Cases coded with the unable to participate disposition often are considered eligible cases in calculating survey response rates.

A variety of permanent and temporary reasons may cause respondents to be unable to participate in a survey. Permanent reasons for being unable to participate in a survey include language barriers, physical or mental disabilities, and chronic severe illnesses. The sampled respondent in a telephone or in-person survey may not speak English (or another target language) well enough to complete the interview. Respondents with ...