Incentive delivery timing and follow-up survey completion in a prospective cohort study of injured children: a randomized experiment comparing prepaid and postpaid incentives

Retaining participants over time is a frequent challenge in research studies evaluating long-term health outcomes. This study's objective was to compare the impact of prepaid and postpaid incentives on response to a six-month follow-up survey.We conducted an experiment to compare response between participants randomized to receive either prepaid or postpaid cash card incentives within a multisite study of children under 15 years in age who were...