Recruiting Probability Samples for a Multi-Mode Research Panel with Internet and Mail Components

Survey response rates have been declining over the past several decades, particularly for random-digit-dialing (RDD) telephone surveys (see de Leeuw and de Heer 2002; Steeh 1981). This trend affects research panels such as the Gallup Panel, which uses RDD methodology to recruit its members. If significant improvements in panel recruitment response rates are to be achieved, new approaches must be considered. This paper presents the findings of a mail and telephone mode experiment conducted by the Gallup Panel to analyze the individual and combined effects of incentives, advance letters, and follow-up telephone calls on the panel recruitment response rate. Study results indicate that the mail recruitment approach nets a higher panel response rate, and that the cost-effectiveness of the mail recruitment approach is significantly greater than the telephone recruitment approach. Study results also suggest that the advance letter, incentive, and telephone follow-up conditions all have independent, positive influences on the response rate; and that the groups that receive an advance letter, that receive incentives, and that receive a follow-up telephone call have higher panel recruitment response rates than the control group.