Directory sampling is one of the earliest versions of telephone sampling. Telephone directories consist of listings of telephone numbers. The residential numbers are generally placed in a section of the directory separate from business numbers. Each telephone listing is generally accompanied by a name and an address, although the address is not always present. Households may choose not to have their telephone number published in the directory. These are referred to as unpublished numbers, most of which also are unlisted numbers.

In the original application of directory sampling, a set of telephone directories covering the geopolitical area of interest to the survey were assembled. After the sample size of telephone numbers was determined, a random selection procedure was used to draw the required number of residential ...