Herding in Collective Action

Last registered on November 27, 2021

Pre-Trial

Trial Information

General Information

Title
Herding in Collective Action
RCT ID
AEARCTR-0008397
Initial registration date
November 21, 2021
Last updated
November 27, 2021, 4:42 PM EST

Locations

Region
Region
Region

Primary Investigator

Affiliation
Universidad de los Andes

Other Primary Investigator(s)

PI Affiliation
Universidad Carlos III Madrid
PI Affiliation
Universidad de los Andes

Additional Trial Information

Status
In development
Start date
2021-11-22
End date
2021-12-23
Secondary IDs
Prior work
This trial is based on or builds upon one or more prior RCTs.
Abstract
We present a field experiment designed to understand the role of herding in collective action, and to disentangle the mechanisms that can drive it. Subjects will be exposed to online petitions via Facebook ads. They will be given messages containing information about the number of individuals who signed each petition, and about their attitudes towards petition. By comparing the fraction of subjects who signed the petition after each message, we will be able to observe the effect that knowledge of participation by others has on individual decisions to participate. We will also observe the extent to which this effect is driven by concerns about being pivotal, or by the willingness to be a part of a successful political movement.
External Link(s)

Registration Citation

Citation
Cardenas, Juan-Camilo, Boris Ginzburg and Jose-Alberto Guerra. 2021. "Herding in Collective Action." AEA RCT Registry. November 27. https://doi.org/10.1257/rct.8397-1.0
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
Facebook ads promoting online petitions with varying information about number of signatures
Intervention Start Date
2021-11-22
Intervention End Date
2021-12-23

Primary Outcomes

Primary Outcomes (end points)
Probability of clicking on the link to sign the petition for each message.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
probability of reacting (interacting with the full length of the message, liking, sharing, commenting) to the Facebook ad.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The field experiment will be conducted via Facebook using several online petitions about protecting the environment. The experiment will consist of two phases. In Phase 1, we will use an online petition which will have around 799 thousand signatures. In Phase 2, we will use a different set of petitions having more than 4 million signatures. A different subject pool will be used for each petition.
Each subject will observe an ad with a link to a petition, an invitation to sign it, and one of several messages of factual information without deception. The messages will constitute our main treatment variation.
Experimental Design Details
In Phase 1, we use a petition with close to 800,000 signatures (Apoya a los defensores de la Tierra), we will have the following treatments (i.e. informative messages before the actual wording of the petition):
Treatment 1.1: a message saying that “more than 700,000 individuals have already signed the petition”.
Treatment 1.2: a message saying that “more than 799,000 individuals have already signed the petition”.
Treatment 1.3: a message saying that “less than 100,000 signatures are left to reach 800,000”
Treatment 1.4: a message saying that “less than 1,000 signatures are left to reach 800,000”
Treatment 1.5: a message saying that “less than 100,000 signatures are left to reach 800,000. If we reach them we will keep this ad running for another week”
Treatment 1.6: a message saying that “less than 100,000 signatures are left to reach 800,000. If we reach them we will keep this ad running for another week”

In Phase 2, we exploit a petition having more than 4 million signatures ( Mega Petición por un Mundo 100% Limpio) we will have the following treatments (i.e. informative messages before the actual wording of the petition):
Treatment 2.1 (2.1a): a message saying that “more than x (X) thousand individuals have already signed the petition”.
Treatment 2.2 (2.2.a): a message saying that “more than x (X) thousand individuals have already signed the petition, more than 10% of individuals in a survey are confident about online petitions improving their quality of life”.
Treatment 2.3 (2.3a): a message saying that “more than x (X) thousand individuals have already signed the petition, almost 90% of individuals in a survey are confident about online petitions improving their quality of life”.
In the above treatments X and x are numbers that are smaller than the true number of signatures, with X>x. The data on attitudes towards petitions comes from a prior survey implemented with University students, this information will be included at the end of the ad. X=4,000,000, x=4,000
Data we hope to collect
For each subject, we will observe whether she has engaged with the ad, whether she clicked on the link to sign the petition, her demographic characteristics, and, potentially, whether she has reacted to the Facebook ad (that is, left a like, a comment, or shared the post).
Variables that we would be interested in obtaining from the individuals who see the ad:
1. What is your date of birth? (dd / mm / yyyy):
2. What gender do you identify with?
- Female
- Male
- Other
3. In politics we usually speak about Left and Right. On a scale where 1 is the Left and 5 is the Right. Where would you place yourself? 1 2 3 4 5
4. What is your place of residence (City, Country)?
5. Would you say that most people can be trusted or that one is never careful enough in dealing with others?
- Most people can be trusted
- One is never careful enough in dealing with others

Target population
We hope to deliver these announcements to Facebook users in Colombia, Mexico, and Argentina.
Ideally, each ad should be sent to between 8,000-10,000 users, the ad should stay active for maximum 7 days
Randomization Method
Randomization done by Facebook algorithm.
Randomization Unit
Individual, that is, Facebook user
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
Cluster is the same as Facebook users
Sample size: planned number of observations
between 8,000 to 10,000 Facebook users per ad
Sample size (or number of clusters) by treatment arms
Phase 1: 10,000 Facebook users per Treatment message (in total, 60,000 users)

Phase 2: 8,000 Facebook users per Treatment message (in Total 48,000 users)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Phase 1-2: 5pp change in the probability of interacting with the ad when using the larger number of signatures (see IRB proposal for more details)
Supporting Documents and Materials

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IRB

Institutional Review Boards (IRBs)

IRB Name
Comité de Ética de Investigación de la Universidad de los Andes
IRB Approval Date
2020-08-31
IRB Approval Number
Acta No. 1231 de 2020
Analysis Plan

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Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
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