The Medicare Current Beneficiary Survey (MCBS) serves as the leading source of information on the Medicare program. As a longitudinal, nationally representative survey, a new panel of Medicare beneficiaries is selected to join the survey each fall. Due to the COVID-19 pandemic, outreach and interviewing for new sample shifted from in-person to phone, supplemented by expanded mailings. This lent urgency to identifying alternate forms of respondent outreach, such as modified mailing strategies and encourage respondent-initiated calls to the project hotline. In Fall 2021, we used an experiment to compare reminder mailing approaches for newly sampled beneficiaries. Cases still pending 4 to 5 weeks after data collection began were randomly assigned to receive either a FedEx reminder letter, a reminder postcard, or no reminder. The control group received a FedEx reminder letter after 12 weeks of data collection. The impact of reminder mailing types on respondent inbound call rates, completion rates, timelines, and interviewer effort required to complete a case was analyzed, along with the implications of the tradeoffs between mailing costs, operational efficiency, and response rates.
