Table 1 Key components of STORE study customer intercept interview protocol

Staffing

 • Teams of two data collectors

 • 2–4 hour data collection shifts

 • Shifts scheduled between 9:00 am and 8:00 pm, 7 days per week

 • Active data collection at each store lasted 30–45 min

Recruitment

 • Data collectors asked permission from store owners, managers, or employees to conduct data collection

 • Data collectors stood outside the store on either side of the primary exit or between the exit and the parking area

 • Data collectors wore t-shirts with the university’s logo and colors and wore a university identification badge on a lanyard around their neck

 • Data collectors held clipboards to their chest with a full-page, color recruitment flyer attached to the back that customers could see as they passed

 • All adults with a visible food, beverage, or bag of purchases were invited to participate (visual eligibility screen)

 • If a group left the store together, all adults in the group with visible purchases were approached and all who were interested were invited to participate

 • Data collectors followed a recruitment script, conducted a verbal eligibility screen, read an informed consent statement, and gave participants written information about the study

 • Reason for ineligibility or refusal, apparent gender, and apparent race/ethnicity were recorded for non-participants

Data Collection

 • Data collectors conducted the interview verbally and recorded detailed information on each food and beverage item purchased (product name, size, quantity, price paid)

 • If a participant did not have a receipt for their food/beverage purchase, data collectors re-entered the store at the end of the visit to verify prices

Participation Incentive

 • Participants were given a $10 gift card after completing the interview