Table 1.

Overview of study variables

Aims and variables	Definitions
Recruitment approach	Instagram, Facebook, Twitter, Reddit, Family/Other Referral, Organic (e.g., unpaid social media posts by study staff)
Aim 1. Reach, cost, and study enrollment
Impressions	Number of times advertisements were displayed
Reach	Number of people who saw advertisements
Advertisement costs	Costs of serving advertisements recorded by social media advertisement analytics platforms
Labor costs	Labor costs of recruitment, tracked by project staff
Screened	Individual completed a brief online screening questionnaire
Eligible	Individual determined to be eligible based on responses to screening questionnaire
Consented	Eligible individual who submitted an online informed consent form
Enrolled	Consented individual who completed an online baseline survey
Excluded	Participant excluded by study staff due to suspicious activity (e.g., attempting to re-enroll using a different name or email address)
Aim 2. Representativeness
Demographics	Age, sex, sexual orientation, educational attainment, annual income
Skin cancer-related variables	Race, ethnicity, degree of tanning/burning that occurs in the sun, whether participants had received a full body skin cancer examination by a healthcare provider in the last 12 months