Benjamin Fredua
National Center for Immunization and Respiratory Diseases and Leidos Health, Inc.
The Impact of Voicemail Messages on RDD Cell-Phone Response Rates in the National Immunization Surveys
Laurie D. Elam-Evans
National Center for Immunization and Respiratory Diseases
Benjamin Fredua
National Center for Immunization and Respiratory Diseases and Leidos Health, Inc.
Holly A. Hill
National Center for Immunization and Respiratory Diseases
Benjamin Skalland
NORC at the University of Chicago
Chalanda Smith
National Center for Immunization and Respiratory Diseases
Vince Welch
NORC at the University of Chicago
The National Immunization Surveys (NIS) are cell-phone random-digit-dial (RDD) surveys to assess vaccination coverage in the U.S. among children. The most common NIS call outcome is reaching voicemail. Standard NIS protocol is to leave a message the 4th time a respondent's voicemail is encountered. The message that is left is a pre-recorded message rather than a message left live by the interviewer making the call. In Q3/2018, both the timing of the message - i.e., whether the message was left on the 1st, 2nd, 3rd, or 4th voicemail event - and the gender and age of the pre-recorded voice were varied. In Q4/2018, the timing, the gender, and the pacing of the pre-recorded message were varied. We compare respondent contact and cooperation rates among the treatment groups to estimate the effect of (1) leaving vs. not leaving a message, (2) leaving a message on the 1st vs. 2nd voicemail event, (3) the voice used on the message, and (4) the pacing of the message. We find that messages decreased contact rates but increased cooperation, resulting in a higher yield rate of completed interviews; we do not observe a difference by message timing; and we find that the voice used had an impact.