NEW UPDATE: Completed trials may now upload and register supplementary documents (e.g. null results reports, populated pre-analysis plans, or post-trial results reports) in the Post Trial section under Reports, Papers, & Other Materials.
Social Image Concerns of Blood Donors
Initial registration date
October 28, 2019
October 29, 2019 9:47 AM EDT
This section is unavailable to the public. Use the button below
to request access to this information.
European University Institute
Other Primary Investigator(s)
University of Bonn
Additional Trial Information
We study experimentally the role of social image concerns for blood donors.
Field experiment in collaboration with Italian NGO to study short and long term effects of social recognition.
Intervention Start Date
Intervention End Date
Primary Outcomes (end points)
Blood donations made in November 2019
Plasma donations made in November 2019
Blood donations made in November 2020
Plasma donations made in November 2020
Primary Outcomes (explanation)
To assess the short [long] term effects of visibility incentives on blood (plasma) donations we compare blood (plasma) donations made in November 2019  between treatments ii and iv (iii and v).
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
We will look into whether treatment effects are stronger
- for women than for men;
- for inactive donors (those who have not donated in the last 24 months) than for active donors.
The experiment randomizes whether registered blood donors are offered a public acknowledgment on social media for donating blood in a certain period of time.
Experimental Design Details
randomization done in office by a computer
Some of the treatments are randomized across clusters, and some treatments are randomized within clusters.
Was the treatment clustered?
Sample size: planned number of clusters
65 local branches of the NGO
Sample size: planned number of observations
about 15,000 blood donors
Sample size (or number of clusters) by treatment arms
For the main treatments, we have about 20 clusters per treatment with about 5,000 donors each.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
INSTITUTIONAL REVIEW BOARDS (IRBs)
German Association for Experimental Economic Research e.V.
IRB Approval Date
IRB Approval Number