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Mechanisms of Social Influence: Experimental Evidence from Blood Donations
Last registered on March 01, 2021

Pre-Trial

Trial Information
General Information
Title
Mechanisms of Social Influence: Experimental Evidence from Blood Donations
RCT ID
AEARCTR-0007266
Initial registration date
February 28, 2021
Last updated
March 01, 2021 10:41 AM EST
Location(s)

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Primary Investigator
Affiliation
University of Essex
Other Primary Investigator(s)
PI Affiliation
University of Bonn
Additional Trial Information
Status
In development
Start date
2021-03-01
End date
2021-09-30
Secondary IDs
Abstract
In this study we aim to identify the effect of social influence interventions in motivating volunteering behavior, in the setting of blood donations. We develop a novel experimental design to disentangle social pressure from social recognition motives. We vary other aspects of the social influence intervention (communication channel and social proximity of peers) to inform theory as well as practical implementation challenges of behavioral interventions that are implemented at a large scale.
External Link(s)
Registration Citation
Citation
Goette, Lorenz and Egon Tripodi. 2021. "Mechanisms of Social Influence: Experimental Evidence from Blood Donations." AEA RCT Registry. March 01. https://doi.org/10.1257/rct.7266-1.0.
Sponsors & Partners

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Experimental Details
Interventions
Intervention(s)
Intervention Start Date
2021-03-01
Intervention End Date
2021-04-16
Primary Outcomes
Primary Outcomes (end points)
Donations in March 2021
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
The experiment has 4 main treatments that are delivered via WhatsApp to donors:
- Social pressure in groups with high social proximity
- Social pressure + social recognition in groups with high social proximity
- Social pressure in groups with low social proximity
- Social pressure + social recognition in groups with low social proximity

Two control groups:
- Baseline message
- No message

Three additional treatment groups:
- Social recognition via Facebook post (sent via Whatsapp)
- Social recognition via Facebook post (sent via email)
- Baseline message (sent via email)
Experimental Design Details
Not available
Randomization Method
randomization done in office by a computer
Randomization Unit
group of donors
Was the treatment clustered?
Yes
Experiment Characteristics
Sample size: planned number of clusters
2000 groups of donors
Sample size: planned number of observations
40000 donors
Sample size (or number of clusters) by treatment arms
220
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
University of Essex, Ethics Sub Committee 1
IRB Approval Date
2021-02-09
IRB Approval Number
ETH2021-0488