Time-Based and Milestone-Based Feedback in Public Goods Provision (Online Laboratory Experiments)

Last registered on May 01, 2022

Pre-Trial

Trial Information

General Information

Title
Time-Based and Milestone-Based Feedback in Public Goods Provision (Online Laboratory Experiments)
RCT ID
AEARCTR-0008445
Initial registration date
November 05, 2021

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
November 08, 2021, 10:13 AM EST

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

Last updated
May 01, 2022, 8:48 AM EDT

Last updated is the most recent time when changes to the trial's registration were published.

Locations

Region

Primary Investigator

Affiliation
University of Exeter

Other Primary Investigator(s)

PI Affiliation
University of Melbourne
PI Affiliation
University of Melbourne

Additional Trial Information

Status
Withdrawn
Start date
2021-11-09
End date
2023-12-31
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
The goal of this research is to use insights from behavioral economics to mitigate the free-riding problem in public goods games. We will examine the role of real-time feedback versus intermediate goals (milestones) in shaping dynamic contributions to a public good. Individuals can contribute to the same public good from a fixed endowment over multiple time periods, and they receive different types of feedback at the end of each period depending on treatment assignment. This research will contribute to the well-established literature on voluntary contribution mechanism.
External Link(s)

Registration Citation

Citation
Erkal, Nisvan, Boon Han Koh and Nguyen Lam. 2022. "Time-Based and Milestone-Based Feedback in Public Goods Provision (Online Laboratory Experiments)." AEA RCT Registry. May 01. https://doi.org/10.1257/rct.8445-2.0
Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2021-11-09
Intervention End Date
2023-12-31

Primary Outcomes

Primary Outcomes (end points)
1) Total group contributions at the end of each sequence
2) Total group contributions at the end of each round within the sequence
3) Proportion of groups with total contributions meeting specific thresholds/milestones at the end of each sequence
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
1) Individual contributions by group members in each round within the sequence
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
[Study has been withdrawn as we decided to implement the experiment face-to-face instead of online, given the easing of COVID-19 restrictions in Australia.]

Participants take part in five sequences of a public goods game with dynamic contributions. At the beginning of each sequence, participants are divided into groups of four (random rematching across sequences), and each group member is given an endowment of 50 tokens. Each sequence consists of 10 rounds where, in each round, group members can decide how much of their remaining endowment to contribute to the Group Account. Any unassigned tokens at the end of the 10th round will remain in the members' Private Accounts. Group members receive their payoffs from the Group and Private Accounts only at the end of the 10th round.

Payoffs follow the standard VCM experiment: For every token remaining in a group member's Private Account, that member receives 1 token. For every token there is in the Group Account, each group member receives 0.4 tokens.

The main treatments vary on the information that group members receive at the end of each round of the sequence, with feedback being either time-based or milestone-based. Where feedback is milestone-based, we will also vary the intervals of the milestones.
Experimental Design Details
Participants take part in five sequences of a public goods game with dynamic contributions. At the beginning of each sequence, participants are divided into groups of four (random rematching across sequences), and each group member is given an endowment of 50 tokens. Each sequence consists of 10 rounds where, in each round, group members can decide how much of their remaining endowment to contribute to the Group Account. Any unassigned tokens at the end of the 10th round will remain in the members' Private Accounts. Group members receive their payoffs from the Group and Private Accounts only at the end of the 10th round.

Payoffs follow the standard VCM experiment: For every token remaining in a group member's Private Account, that member receives 1 token. For every token there is in the Group Account, each group member receives 0.4 tokens.

The main treatments vary on the information that group members receive at the end of each round of the sequence:
- In Treatment T (Time), participants are informed how many tokens have been accumulated in the Group Account at that point in the sequence.
- In Treatment M25 (Milestone-25), participants are informed whether the accumulated number of tokens in the Group Account has met the thresholds of 25, 50, 75, 100, 125, 150, 175, or 200.
- In Treatment M50 (Milestone-50), participants are informed whether the accumulated number of tokens in the Group Account has met the thresholds of 50, 100, 150, or 200.

After the main task is completed, participants also complete a conditional cooperation task (similar to Fischbacher et al., 2001 and Fischbacher and G├Ąchter, 2010). Participants will also be asked to complete a questionnaire eliciting their demographic characteristics, reasons for their decisions in the experiment, as well as decisions in a one-shot risk task (Gneezy and Potters, 1997).
Randomization Method
Randomization is done at the session level. Treatment assignment is randomly pre-determined before the session is run, and participants select into sessions randomly without knowing the pre-determined treatment assignment.
Randomization Unit
Unit of randomization is at the experimental session level
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
21 to 24 (depending on show-up rate for each session)
Sample size: planned number of observations
480
Sample size (or number of clusters) by treatment arms
160 (between 7 and 8 sessions each with 20 or 24 participants, depending on show-up rate)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We consider effect sizes for group contributions at the end of each sequence. The main unit of observation in our analysis is at the group-sequence level. With each group of 4 participating in 5 sequences, 160 participants yield 40 groups or, equivalently, 200 group-sequences. For a Type I error rate of 0.05 and statistical power of 0.80 under a two-tailed test, this gives us an effect size of 0.287 standard deviations (between small and medium).
IRB

Institutional Review Boards (IRBs)

IRB Name
Business and Economics & Melbourne Business School Human Ethics Advisory Group (University of Melbourne)
IRB Approval Date
2020-10-13
IRB Approval Number
2021-14599-20266
IRB Name
School of Economics Research Ethics Subcommittee (University of East Anglia)
IRB Approval Date
2021-09-02
IRB Approval Number
ETH2122-0016

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