Random-digit dialing (RDD)

Technique used in studies employing telephone interviews in which the numbers to be called are randomly generated. RDD consists of selecting all digit (10) telephone numbers at random. Although this approach gives all households with telephones an approximately equal chance being included in the sample, it suffers from limitations. It is costly and time consuming to implement because all possible telephone numbers are not in service. Also RDD does not distinguish between telephone numbers that are of interest and those that are not.