A Reassessment of List-Assisted RDD Methodology

Random digit dial (RDD) sampling methodology was developed over two decades ago when local telephone exchanges used 100-series telephone banks as physical building blocks for telephone number assignment. During the intervening decades the telecommunication industry has undergone a number of fundamental changes that have had drastic effects on the efficiency and coverage of RDD samples. Based on a new study of landline telephone numbers, which was conducted during the second quarter of 2008, this paper reexamines the assumptions that are relied upon for construction of list-assisted RDD samples; quantifies the extent of undercoverage in the corresponding sampling frames; investigates alternative methods of frame construction for RDD samples; and evaluates other sample design options that can offer greater coverage with varying degrees of efficiency.