Referrals, Cooperation, and Competition

Last registered on April 30, 2025

Pre-Trial

Trial Information

General Information

Title
Referrals, Cooperation, and Competition
RCT ID
AEARCTR-0015842
Initial registration date
April 22, 2025

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
April 30, 2025, 8:39 AM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Primary Investigator

Affiliation
Luxembourg Institute of Socio-Economic Research

Other Primary Investigator(s)

Additional Trial Information

Status
In development
Start date
2025-04-21
End date
2025-05-16
Secondary IDs
Prior work
This trial is based on or builds upon one or more prior RCTs.
Abstract
This study investigates how referral sources (vertical referrals, horizontal referral, or direct invitation) influence students' choices regarding cooperation and competition in an application process for a university excellence award. Using an online real-effort task (counting ones in 4x4 matrices), students complete the task individually, then in a cooperative and competitive format. Participants probabilistically select their preferred referral source to be matched with, allowing the measurement of revealed preferences and belief-driven behavior. The order of cooperation and competition tasks is randomized across participants.
External Link(s)

Registration Citation

Citation
Munoz, Manuel. 2025. "Referrals, Cooperation, and Competition." AEA RCT Registry. April 30. https://doi.org/10.1257/rct.15842-1.0
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
Participants are invited to apply for the Academic Excellence Award through one of three channels:
- Faculty Referral: Recommended by university faculty.
- Peer Referral: Recommended by another student applicant.
- Direct Invitation: Invited directly by the university without referral.

The third stage of the application process consists of:
1. Belief Elicitation: Participants estimate participation and average performance by referral group.
2. Real-Effort Tasks:
- Part B: Individual task (1 min), earns 1 point per correct answer.
- Part C: Competition task (1 min); participants probabilistically assign chances to be paired with a competitor from each referral group.
Winner earns 2 points per correct answer; loser earns 0.5.
- Part D: Cooperation task (1 min); participants assign chances to be paired with a teammate from each referral group. Team score is
average number of correct answers × 1.5.
- The order of competition and cooperation is randomized across participants.
Intervention (Hidden)
Intervention Start Date
2025-04-21
Intervention End Date
2025-05-16

Primary Outcomes

Primary Outcomes (end points)
- Partner/Competitor Selection
- Beliefs
Primary Outcomes (explanation)
- Partner/Competitor Selection: Distribution of assigned probabilities to each referral group.
- Beliefs: Accuracy and distribution of elicited beliefs about performance and participation by referral group.

Secondary Outcomes

Secondary Outcomes (end points)
- Task Performance
- Consistency between Beliefs and Choices
- Quality of Justification
Secondary Outcomes (explanation)
- Task Performance: Number of correctly solved matrices across individual, cooperative, and competitive tasks.
- Consistency between Beliefs and Choices: Correlation between beliefs and probabilistic partner/competitor assignment.
- Quality of Justification: Qualitative coding of open-ended rationales for probabilistic assignments.

Experimental Design

Experimental Design
The expected number of participants to reach this stage of the application process and thus participate in the experiment is about 1020. The number from each group is expected to be:

- Faculty referred: ~127
- Peer referred: ~ 173
- Directly invited: ~ 720

Participants are randomly assigned (stratified by referral source) to one of two task sequences:

- Sequence 1: Cooperation → Competition
- Sequence 2: Competition → Cooperation

This design controls for order effects and enables estimation of how referral identity affects preference in collaborative versus competitive settings.

The primary outcomes focus on partner/competitor selection and belief accuracy. I will test the following hypotheses:

Hypothesis 1 (Competition): Participants are more likely to allocate probabilities to compete against applicants directly invited or referred by peers rather than those referred by faculty.

H1 reflects expectations about lower ability of peer/direct-invite groups compared to faculty referrals.

Hypothesis 2 (Cooperation): Participants are more likely to allocate probabilities to cooperate with applicants referred by faculty rather than peers or direct invites.

H2 reflects expectations about higher ability or greater trustworthiness among faculty referrals.

Hypothesis 3 (Referral homophily): Participants are more likely to assign higher probabilities to partners/competitors who share the same referral source as themselves (faculty referred select faculty, peer referred select peer, etc.).

H3 tests if homophiily is a heuristic driving selection and whether it is stronger than following the reported beliefs.

Hypothesis 4 (Belief-driven choice): Participants’ selections (probability allocations) will be positively correlated with their stated beliefs about the performance of each group.

Hypothesis 5 (Null order effects): The order in which competition and cooperation tasks are completed will not significantly affect partner/competitor selection patterns.
Experimental Design Details
Randomization Method
Randomization into task sequences (cooperation-first or competition-first) is done inside the online experiment in Qualtrics, stratified by referral source.
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
n/a
Sample size: planned number of observations
Expected participants: 1020 = 127 (Faculty referred) + 173 (Peer referred) + 720 (Directly invited)
Sample size (or number of clusters) by treatment arms
n/a
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Assuming a significance level of 0.05, statistical power of 0.80, and a binary outcome based on selection preference (baseline probability of 33.3%), the minimum detectable effect size (MDE) between the smallest referral group (faculty, N=127) and any other group is approximately 11.6 percentage points. This reflects the smallest difference in selection probability that can be detected with adequate power in pairwise group comparisons. Calculations assume independent observations and no clustering.
IRB

Institutional Review Boards (IRBs)

IRB Name
LISER Research Ethics Committee
IRB Approval Date
2025-04-07
IRB Approval Number
LISER REC/2025/142.ROPE

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