Table 2 An example SMS message a participant in the intervention group receives during the intervention period

Thank you for completing another month in the FEEDBACK trial. Your safe driving account currently has a balance of $120, and your new safe driving target is: only yellow, light, or dark green DrivePoints scores, with no more than ONE yellow over the next four weeks. If you fall short of this safe-driving target, you will lose $24 from your safe-driving account.