Intervention (Hidden)
In a natural field experiment (RCT), we randomly vary invitations to an existing activity of a major stem cell donor center, aimed at increasing the willingness of registered donors to be available at the confirmatory typing stage. The activity asks donors to fill out a health questionnaire, and to report any periods longer than three weeks that would preclude donation. The experimental interventions consist of an invitation by means of a physical letter followed by an email, both with the same framing and activity. We run two treatments and a baseline group. For internal evaluation purposes, the donor center runs another baseline group using the letter and email from prior to the intervention. In the treatments, letters and emails are both framed so that donors either belong to (intervention i) a team of “quickly available donors,” or (intervention ii) a team of “highly engaged” donors. The baseline group receives a letter (and email) with neither framing. The activity itself, completing a short medical survey and indicating unavailability dates, is the same for all invitees, and is voluntary. Not participating has no consequences for the donor, who will remain in the donor registry. No one can participate in the activity who is not invited.
As part of the intervention, we send the invitations to around 400,000 registered donors in the stem cell donor center. We evaluate the take-up rate (participation) in the activity, the frequency of reporting absences, and most importantly, whether a donor proceeds with confirmatory typing when called upon (primary outcome). The donor center is able to match administrative data on potential donors who are sent an invitation to participate in the activity. For instance, data includes information from when potential donors initially registered and data from the field experiment. All donor related data stays within the donor center.
This study can help answer the following primary research questions:
How does additional donor effort before a donation request affect subsequent donation availability?
How does donor identity (i.e. being an “engaged” or “quickly available” donor) matter for following through with donation, participating in the activity, and reporting absences?
Given the research questions, we will test for differences in outcomes between the three invitations sent out.
The trial end date is dependent on receiving 6,000 CT requests from the three treatment letters (based on our 400,000 invitations). When this number is reached, we will stop the trial. If this number is not reached by 5 years, the trial will also be stopped.
UPDATE:
Invitations to the experiment were stopped by the executive board of the donor center on June 22, 2022. Hence, data collection commenced after the first invitations were sent out and will be stopped either one and a half years after the last invitation was sent out (December 22, 2023) or after 150 CT requests per treatment arm have been collected (depending on what happens first).