Table 1.

Costs associated with each recruitment method used in the study.

Recruitment stage	Recruitment method tasks and their costs (US $)
	News feed	Clinic	Snowball sampling	Other methods
Start-up	2 hours ($64.76a) to select image, slogan, and Facebook campaign settings $125.00 to have HIPAAb-compliant webformc	1 hour ($32.38) to design flyer	30 minutes ($16.19) to explain study to each of two snowball sample leaders ($32.38 total)	30 minutes ($16.19) to discuss referral system with principal investigator of previous study
Display advertisement	$0.012 per viewer for Facebook impression	1.14 minutes ($0.62) to screen chartd 30 minutes ($16.19) per viewer to wait in clinic and find opportunity to approach participant	$0.00 (done by snowball sample leaders)	$0.00 (combined into below email that arranged screening)
Provide more information to inquirerse	$0.00 for initial clickers (directed automatically to webform page) 5 minutes ($2.70) per webform completer to send email template and follow up by phonee	1 color flyer ($0.20) per inquirer 5 minutes ($2.70) per inquirer to verbally explain study and answer questions	5 minutes ($2.70) per inquirer to send email template and follow up by phonee	5 minutes ($2.70) per inquirer to send email template and follow up by phonee
Screening session with responsive volunteers	15 minutes ($8.10) per volunteer to answer further questions about study and ask screening questions	15 minutes ($8.10) per volunteer to answer further questions about study and ask screening questions	15 minutes ($8.10) per volunteer to answer further questions about study and ask screening questions	15 minutes ($8.10) per volunteer to answer further questions about study and ask screening questions

^aPersonnel rate of $32.38/hour based on principal investigator’s salary + fringe.

^bHIPAA: Health Insurance Portability and Accountability Act.

^cReflects 1 month of institutional subscription to Qualtrics (simulates larger trial where 20 days of advertising would occur in a single month).

^dCalculated as 1 minute per chart / (88% of charts meeting age and type 1 diabetes diagnosis criteria) = 1.14 minutes per qualifying chart.

^eIndividuals not responding to first phone call were considered unresponsive.