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Understanding Mechanisms of Persistence in Prosocial Behavior
Last registered on March 15, 2021

Pre-Trial

Trial Information
General Information
Title
Understanding Mechanisms of Persistence in Prosocial Behavior
RCT ID
AEARCTR-0007366
Initial registration date
March 15, 2021
Last updated
March 15, 2021 10:49 AM EDT
Location(s)
Region
Primary Investigator
Affiliation
University of Zurich
Other Primary Investigator(s)
PI Affiliation
University of Essex
PI Affiliation
University of Lausanne
PI Affiliation
National University of Singapore
Additional Trial Information
Status
Completed
Start date
2015-03-01
End date
2016-12-31
Secondary IDs
Abstract
We test whether asking individuals to donate blood leads to a persistent change in behavior, and examine the underlying mechanism. In a field experiment, we randomize a phone call, asking blood donors to turn out, and follow them over up to 18 months. We observe significant behavioral persistence for at least one year. We use naturally occurring rainfall as a second instrument for donor turnout to test whether behavioral persistence is due to habit formation (Stigler and Becker, 1977) or a persistent increase in motivation independent of past donation. Our results strongly favor habit formation as the underlying mechanism.
External Link(s)
Registration Citation
Citation
Bruhin, Adrian et al. 2021. "Understanding Mechanisms of Persistence in Prosocial Behavior." AEA RCT Registry. March 15. https://doi.org/10.1257/rct.7366-1.0.
Experimental Details
Interventions
Intervention(s)
Phone call asking pre-registered donors two days before the upcoming blood drive to make a donation.
Intervention Start Date
2015-03-01
Intervention End Date
2016-12-31
Primary Outcomes
Primary Outcomes (end points)
Blood donation turnout (binary)
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
4 experimental conditions: In the first condition, C1, donors receive a phone call only in period 1. In the second condition, C2, donors receive a phone call only in period 2, i.e., six months after the donors in condition C1. In the third condition, C12, donors receive a phone call in both periods 1 and 2. In the control condition, donors do not receive any phone calls. There are no further phone calls in periods 3 and 4, i.e., 12 and 18 months later. However, we keep observing donation outcomes in periods 3 and 4.
Experimental Design Details
Randomization Method
Randomization done by a computer
Randomization Unit
Individual
Was the treatment clustered?
Yes
Experiment Characteristics
Sample size: planned number of clusters
1400
Sample size: planned number of observations
5600
Sample size (or number of clusters) by treatment arms
350 individuals in each treatment condition
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
IRB Approval Date
IRB Approval Number
Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
No
Is data collection complete?
Data Publication
Data Publication
Is public data available?
No
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)
REPORTS & OTHER MATERIALS