The Effects of Input Heterogeneity and Rotational Water Allocation on Cooperative Behavior: Evidence from a Lab-in-the-Field Experiment

Last registered on March 19, 2025
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Pre-Trial

Trial Information

General Information

Title
The Effects of Input Heterogeneity and Rotational Water Allocation on Cooperative Behavior: Evidence from a Lab-in-the-Field Experiment
RCT ID
AEARCTR-0015549
Initial registration date
March 15, 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
March 19, 2025, 9:25 AM EDT

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

Locations

Country
Ethiopia
Region
Africa

Primary Investigator

Name
Gebreegziabher Fentahun Gugsa
Affiliation
University of Copenhagen
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Other Primary Investigator(s)

PI Name
Goytom Abraha Kahsay
PI Affiliation
University of Copenhagen
Contact Investigator
PI Name
Dagim Belay
PI Affiliation
University of Copenhagen
Contact Investigator
PI Name
Zewdu Berhanie Ayele
PI Affiliation
Bahir Dar University
Contact Investigator

Additional Trial Information

Status
On going
Start date
2025-02-01
End date
2025-04-15
Keywords
Agriculture, Behavior, Environment & Energy, Labor
Additional Keywords
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Managing shared water resources under climate change presents a critical challenge, as free-riding behavior often leads to resource depletion and inefficiencies in irrigation systems. Previous studies have explored cooperative behavior among irrigation users, often employing homogeneous endowment distributions. However, the effects of external interventions involving heterogeneous endowment provisions and rotational water allocation on these cooperative mechanisms remain overlooked. We employ a rotation system, in contrast to earlier research that mostly focused on quota or random water consumption assignment. This proposed study will investigates how labor heterogeneity and rotational water access influence cooperation, investment in watershed management, and equitable water distribution. Using a lab-in-the-field experiment, we will examine how different resource distribution mechanisms shape collective action. The experiment consists of two phases: a baseline phase (Rounds 1–2) and a treatment phase (Rounds 3–7). The baseline phase sets a benchmark for cooperative conduct under consistent circumstances by providing equal labor endowments to all participants and extracting water in a fixed order. Participants are divided into four groups at random during the treatment phase: three treatment groups and a control group. Equal labor endowments and fixed sequential water extraction are maintained in the control group. While maintaining a fixed sequential orders for water extraction, players are randomly assigned various labor endowments in Treatment 1 to create labor heterogeneity. While Treatment 2 maintains similar labor endowments, it introduces a water access system that rotates, with a new turn order each round. Both treatments are combined in Treatment 3.
External Link(s)

Registration Citation

Citation
Ayele, Zewdu Berhanie et al. 2025. "The Effects of Input Heterogeneity and Rotational Water Allocation on Cooperative Behavior: Evidence from a Lab-in-the-Field Experiment." AEA RCT Registry. March 19. https://doi.org/10.1257/rct.15549-1.0
Sponsors & Partners

Sponsors

Partner

Name
University of Copenhagen
Type
government
URL
https://www.ku.dk/en
Name
Bahir Dar University
Type
government
URL
https://www.bdu.edu.et/
Name
Policy Studies Institute
Type
government
URL
https://psi.org.et/
Experimental Details

Interventions

Intervention(s)
The experiment consists seven rounds, including two baseline rounds for practical familiarization (Rounds 1–2) and five treatment rounds (Rounds 3–7). At the beginning of the game, participants are assigned to one of four groups: a control group, a labor heterogeneity treatment group, a rotation treatment group, and a labor heterogeneity and rotation treatment group.

In the control group, participants receive equal labor endowments in every round, participant have uniform capacity to contribute to watershed management. Water allocation follows a fixed sequential order, meaning that players extract water in the same position each round without rotation. This setup serves as a benchmark for evaluating cooperative behavior and strategic decision-making in the absence of external interventions.

In the labor heterogeneity treatment, the fixed water position order remains unchanged, but labor endowments vary in random assignment (lottery) at the beginning of each round. Some players receive higher labor availability than others, representing real world variation in labor force capacity. This treatment examines whether unequal labor distribution affects collective action, investment in watershed management and irrigation canal maintenance, and decisions regarding water extraction when access to irrigation water remains constant.

In the rotation treatment, labor endowments remain uniform across all players, but water allocation follows a rotational system where the extraction order shifts each round. Over five rounds, each player experiences every possible position in the sequence once, ensuring no single player consistently holds an advantage or disadvantage in water access. This intervention assesses how changes in relative water access positions influence cooperation and long-term investment in shared resources.

In the combined treatment, participants experience both rotational water allocation and labor heterogeneity simultaneously. Each round, players are assigned different labor endowments, while the order of water extraction rotates to ensure that all players experience different levels of access over time.
Intervention (Hidden)
Intervention Start Date
2025-02-01
Intervention End Date
2025-04-15

Primary Outcomes

Primary Outcomes (end points)
Cooperation level (Amount of investment in watershed and irrigation management), Amount of Water Extraction and Water Access Equity (fairness in water distribution)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Water Use Patterns and Labor Contribution Variability
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
This experiment is designed as a five player irrigation game to examine the influence of labor heterogeneity and rotational water allocation on cooperation, investment in watershed management, and water use fairness. Ten watershed user group members will be invited as participants and randomly assigned to two groups. Within each group, participants will be randomly assigned positions along a waterway, numbered 1 to 5, reflecting irrigation systems where irrigation users are assigned specific locations along a canal or waterway (1: upstream, 5: downstream). Players will engage in an irrigation game for seven rounds, where they make decisions on labor contributions for watershed management and water extraction. The first two rounds serve as a baseline phase, where all participants receive equal labor endowments, and water extraction follows a fixed sequential order. This stage familiarizes players with the game and establishes a reference point for cooperative behavior before introducing interventions.

The study involves 400 participants, who will be randomly assigned to one of four experimental groups. The first group will serve as the control group and will not receive any intervention.

1. Control Group: Participants continue under equal labor endowments, and position remains fixed in sequence. This serves as a baseline for evaluating changes in behavior under different treatments.
2. Labor Heterogeneity Treatment: Water extraction position remains fixed in sequence, but labor endowments vary across rounds, representing fluctuations and variability in workforce availability. This treatment assesses how disparities in labor resources affect collective action.
3. Rotation Treatment: Labor endowments remain equal, but water extraction follows a rotational system, where extraction positions change across rounds. This intervention examines whether rotating water access influences cooperation and investment.
4. Combined Treatment: Participants experience both labor heterogeneity and rotational water use, meaning that labor endowments differ across rounds while water access follows a rotating sequence.
Experimental Design Details
Randomization Method
We performed randomization through a public lottery
Randomization Unit
Individual level
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
No clusters
Sample size: planned number of observations
The total number of observations is 2800: 400 individuals, each playing 7 rounds
Sample size (or number of clusters) by treatment arms
700 observations (100 individuals playing 7 rounds) for each experimental arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Research Ethics Committee, Faculty of science, University of Copenhagen
IRB Approval Date
2024-06-26
IRB Approval Number
504-0518/24-5000
Analysis Plan

Post-Trial

Post Trial Information

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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