Practical Guidelines for Dual-Frame RDD Survey METHODOLOGY (Now That the Dust is Settling)

For nearly two decades, the traditional sampling methodology of list-assisted landline random digit dialing (RDD) has served as the survey research workhorse for population-based studies. In recent years, however, virtually all RDD surveys have come to rely on dual-frame techniques in an attempt to improve coverage. This change is primarily due to the growing number of households that are abandoning their landline phones and relying exclusively on cellular services (Fahimi and Kulp 2009). Figure 1 shows the geodemographic composition of adults living in households without landline services, highlighting the potential coverage bias that can result should such individuals be excluded from sample surveys. Consequently, the dual-frame RDD (DFRDD) technique has become the standard practice whereby samples of landline telephone numbers are supplemented with cellular numbers to produce probability-based samples of all households, including the so-called cell phone only (CPO) households. While including cellular numbers has offered an effective remedy for improving coverage of the traditional landline samples, current practice of