Random digit dialing is when researchers sample from a compilation of all possible telephone numbers, including unlisted ones (17). Some researchers try to measure public opinion by calling every 50th residential number in a telephone book. This survey method excludes cell phone users, unlisted numbers, and people who do not have a telephone.
Rather than selecting names and numbers of individuals to be called, computers are used to generate random sets of seven-digit numbers, which are then called as the survey sample.
Techniques that form samples by adding random digits to the telephone prefixes that fall within the sampling area so as to include listed (published) and unlisted numbers in the sample.
The method of randomly selecting phone numbers to be called. This is most often done by computer and allows for an equal chance for all the numbers in the sample to be dialed.
A selection of telephone numbers where the digits in the numbers are picked by chance. Within predefined geographic regions.
Random digit dialing (RDD) is a method for selecting people for involvement in telephone statistical surveys by generating telephone numbers at random. Random digit dialing has the advantage that it includes unlisted numbers that would be missed if the numbers were selected from a phone book. In populations where there is a high telephone-ownership rate, it can be a cost efficient way to get complete coverage of a geographic area.