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 every fall. In response to the COVID-19 pandemic, data collection shifted from in-person to phone outreach and survey administration which brought concerns of lower response rates, as well as incomplete data since phone numbers were not available on the sample frame. This placed increased emphasis on the importance of alternate forms of respondent outreach, such as mailings and respondent-driven toll-free calls. The MCBS has long used an advance letter and in Fall 2021, a split ballot experiment tested the effect of different appeals within the advance letter, specifically testing new language prompting panel members to call the survey toll-free number for more information and to schedule an interview. Findings from the impact of the revised appeal on completion rates, timelines, and interviewer effort required to complete a case will help inform how advance materials can be leveraged to increase respondent cooperation and improve efficiency.
