Ineligible

The ineligible disposition is used in all surveys, regardless of the mode (telephone, in-person, mail, or Internet). Ineligible cases are cases that were included in the sampling frame but fail to meet one or more of the criteria for being included in the survey. Cases coded as ineligible do not count in computing survey response rates.

One of the most common reasons a case would be coded as ineligible is when a survey uses screening criteria to determine whether the respondent, household, or organization contacted as part of a survey is eligible to complete the survey. For example, a survey may require respondents or households to be located within a specific geographic area, such as a specific county, town or village, or neighborhood. A case would be considered ineligible if it were discovered that the respondent or household was located outside of the geographic boundaries of the survey population. In most instances, if it were discovered during the screening process that the sampled respondent had moved out of the geographic boundaries of the survey during the field period, that case also would be considered ineligible.

An additional example of how screening criteria may result in a case being considered ineligible occurs in surveys of the general population. These surveys use residential status as screening criteria, and as a result, all cases that result in contact with a nonresidential unit, such as businesses, schools, or governmental organizations, would be considered ineligible. In in-person surveys, this often is discovered when an interviewer visits a sampled address and discovers that it is not a residence. In telephone surveys, this would be discovered when interviewers make telephone calls to businesses; fax or data lines; nonworking, changed, and disconnected telephone numbers and numbers that reach pagers. In landline telephone surveys, numbers that reach cell phones would be treated as ineligible. Also, in a telephone survey an answering machine message [Page 333]might allow an interviewer to determine if the number is ineligible.

Some surveys use screening at the respondent level to determine eligibility. For example, a survey may seek to collect data from respondents with a specific set of characteristics (demographics, occupation, tenure in job, etc.). Cases in which the individual respondent discloses during the screening process that he or she does not have the characteristics sought by the survey would be considered ineligible. Finally, if a telephone, in-person, mail, or Internet survey uses quotas, cases contacted for which quotas have already been filled are considered ineligible.

A number of other reasons that a case may be categorized with the ineligible disposition are specific to each survey mode. In telephone surveys, the ineligible disposition may be used when the number has technical difficulties and no one can be reached on it or when a business number is forwarded to a residence. In an in-person survey, the ineligible disposition may be used for cases in which interviewers discover that the sampled address is a housing unit that is vacant during the entire field period of a survey, and rarely, for a housing unit that has no eligible respondent (such as cases in which all residents are under 18 years of age). In mail and Internet surveys, the ineligible disposition may be used if the same respondent or addressee is sampled more than once. These duplicate mailings usually are treated as ineligible if the error is not caught until after the questionnaires have been mailed out (in mail surveys) or until after the email invitation is sent out (in Internet surveys).

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