Choice-set effects in fairness decisions

Last registered on January 19, 2021


Trial Information

General Information

Choice-set effects in fairness decisions
Initial registration date
January 16, 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
January 19, 2021, 6:19 AM EST

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

Last updated
January 19, 2021, 6:48 AM EST

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



Primary Investigator


Other Primary Investigator(s)

Additional Trial Information

In development
Start date
End date
Secondary IDs
In the present study I conduct a controlled online experiment investigating choice-set effects in fairness decisions. Specifically, I look at range based choice-set effects. That is, the effects of expanding the range of one choice dimension. I use a spectator design with between-subject treatment to expand the range in one dimension of a fairness decision by adding a decoy alternative. Thus, I am able to causally infer how expanding the range of a choice dimension in a fairness decision affects the preference relation between the original alternatives in a choice set.
External Link(s)

Registration Citation

Madland, Kjetil. 2021. "Choice-set effects in fairness decisions." AEA RCT Registry. January 19.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
The primary outcome is the share of spectators in each group who rank alternative 1 as more preferred than alternative 2.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
I study spectator decisions. This way, I can control the effect of choice-set structure on distributive preferences without having to factor in self interest.
Experimental Design Details
Randomization Method
Randomization is done in the Qualtrics experiment
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
1400 individual spectators
Sample size: planned number of observations
1400 individual spectators
Sample size (or number of clusters) by treatment arms
200 individual spectators in each treatment arm of the four choice scenarios.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
With N=200 in each treatment cell, alpha=0.05 and 90 percent statistical power, the smallest detectable effect size is 16 percent. This is about in line with the effect size from the pilot study.

Institutional Review Boards (IRBs)

IRB Name
NHH Internal Review Board by Lars Jacob Tynes Pedersen
IRB Approval Date
IRB Approval Number
NHH-IRB 13/20
Analysis Plan

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Post Trial Information

Study Withdrawal

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials