Segmented or Overlapping Dual Frame Samples in Telephone Surveys

Abstract

Cell phones have produced a dramatic decline in household coverage in telephone surveys using RDD landline sample. Dual frame (landline and cell phone) samples are increasingly used in telephone surveys to address this issue. However, there is no consensus on the best design for dual frame surveys: segmented designs which screen out respondents with landlines from the cell phone (wireless) sampling frame, or overlapping designs which include dual users from both wireless and landline samples. A national telephone survey of 2,501 adults was conducted in May 2009 using an overlapping dual frame design. The two designs can be compared by including (overlapping design) or excluding (segmented design) the dual users from the wireless sample. A comparison of the sample characteristics of this survey to Census population estimates finds the overlapping design generally yields results closer to population parameters than the segmented design. The study also finds significant differences in the characteristics of dual users from the two samples, explaining why the segmented design yields different and potentially less accurate population estimates.