The unavailable respondent survey disposition is used in all types of surveys, regardless of mode. It occurs when the selected respondent for a survey is not available (a) at the time of interview, (b) for some portion of the survey field period (temporarily unavailable), or (c) until after the field period of the survey has ended (permanently unavailable). Cases in which the respondent is unavailable, regardless of the duration, are considered eligible cases in calculating survey response rates.

In most surveys, less than half of the completed interviews result after the first contact with the respondent, regardless of whether that contact occurs in person, by telephone, by mail, or by Internet. Many respondents simply are not available at the time of an [Page 918]interviewer's telephone call ...