Effects of different invitation strategies on participation in a cohort study of Iranian public sector employees: a cluster randomized trial.
Rezvan RajabzadehLeila JananiSeyed Abbas MotevalianPublished in: BMC medical research methodology (2021)
In comparison with the phone call and SMS, the invitation letter is the most effective invitation method for public sector employees to participate in a cohort study. Sending an introduction video did not significantly increase the participation rate compared to sending an invitation letter only.