Unpublished Number

The unpublished number disposition is used both in random-digit dialing (RDD) surveys of the general public and in telephone surveys of named people that use a list-based sample. Unpublished telephone numbers are numbers that are not listed in the local [Page 933]telephone directory, and the vast majority of these numbers also are unlisted and thus not available from directory assistance.

The unpublished number disposition is fairly rare in RDD surveys and is used only when an interviewer dials the telephone number of a case in the sampling pool and receives a recorded message from the local telephone company indicating that the telephone number dialed by the interviewer has been changed to an unpublished number—meaning that the original telephone number in the sampling pool is no longer in service. In RDD surveys of the general public, the new, unpublished number would not be called even in the unlikely possibility that it was known, because doing this would change the household's probability of selection to be included in the sampling pool—essentially doubling the household's chances of being included in the sample. Moreover, because RDD sampling techniques have a nonzero probability of reaching any household in a sampling area that has telephone service, the new, unpublished number also might be included in the sample already. In these cases, the unpublished number disposition would be considered a final disposition.

The unpublished number disposition is used more commonly in telephone surveys that use list-based sampling techniques. For example, if a researcher is sampling households from an address frame and then using reverse directory techniques to match telephone numbers to addresses in the sampling frame, there may be no telephone number available because the household or respondent may have designated his or her number as unpublished. In some cases the researcher may be able to contact directory assistance and obtain a telephone number. However, this does not happen very often because obtaining an unpublished number from directory assistance also requires that the number not also be designated as unlisted by the respondent or household.

The unpublished number disposition usually is considered a final disposition in telephone surveys of specifically named people (i.e. telephone surveys whose sample is a list of specific individuals), because it is highly unlikely that a researcher would be able to discover a telephone number for a sampled respondent or household if directory assistance and reverse directory techniques did not provide one. However, in a mixed-mode survey it might be possible to locate an address and to try to gather data by sending a mail questionnaire or an in-person interviewer to the address. As a result, researchers may consider the unpublished number disposition to be a temporary disposition in mixed-mode surveys.