Survey Flowchart
SECONDARY
The eligibility specified for the 2 random samples were identical. The difference between the denominator for 2 random sample populations is due to the changes/updates to the American Medical Association Physician Masterfile at each date (ie, more physicians becoming eligible at a later date in 2021). Eligible physicians were primary care clinicians with a mailing address in any US state (territories not included) and could have a primary specialty in family practice, general practice, internal medicine, family practice–geriatrics, internal medicine–geriatrics, or geriatric psychiatry and/or a secondary specialty in the same primary specialty categories. USPS indicates United States Postal Service.The demographic characteristics of respondents vs nonrespondents from the AMA data set are shown in eTable 1 in 