Survey mode effects and insurance coverage estimates in the redesigned Gallup well‐being index

Objective To test whether a change from a telephone to mail and Internet survey in January 2018 affected the sample composition and uninsured estimates in the Gallup‐Sharecare Well‐Being Index. Data Sources Gallup‐Sharecare Well‐Being Index (2013‐2018). Study Design Regression discontinuity analysis identified changes after the survey redesign in the estimated U.S. uninsured rate (adults 18‐64) and in the sample's demographic composition. Principal Findings After the survey redesign, the estimated uninsured rate fell 5.3 percentage points ( P  <   0.001), respondents were older and disproportionately white, more likely to have a college degree, and had higher average incomes. These changes were modestly reduced by survey weights. Conclusions The shift to a mail survey (with a web option) led to an older, more educated sample with fewer minorities, and a significant break in trend in the estimated uninsured rate.