Addressing the Cell Phone-Only Problem: Cell Phone Sampling Versus Address Based Sampling

Abstract

Developing cost effective methods for reaching households which no longer have a landline but do have access to a cell phone, so called cell phone only households (CPOs), is a critical item on the agenda of most data collection organizations. Concerns about sample coverage and data biases resulting from the exclusion of CPOs have increased over the past few years as the penetration of CPO households continues to climb, exceeding 50% in some subgroups. To date, two methodologies have emerged as potential means for addressing this issue. The first involves sampling telephone numbers from known cell phone exchanges and calling these numbers or combining these with a sample of landline numbers in a dual frame design. This approach can be further refined by either interviewing all of those who answer the cell phone regardless of whether they have a landline or screening cell phone respondents to identify those living in CPO households. An alternative approach involves sampling of addresses rather than telephone numbers. Address based sampling (ABS) is a new technique built upon the relatively recent availability of large scale address databases. For example, residential address data from the U.S. Postal Service provides nearly 98% coverage of U.S. households. Further, these addresses can be reverse-matched to commercially available databases to identify a relatively large proportion of telephone numbers, facilitating the use of mixed-mode approaches. Here we delineate and compare the advantages and limitations of these two approaches, including discussion of sampling and weighting approaches, operational considerations, timeliness, and cost. We draw examples from several recently conducted studies employing each of these approaches. The findings from this research help bring into sharper focus the potential alternatives to traditional random digit dialed (RDD) telephone surveys for conducting cost effective data collection of the general public.