Fair versus Unfair Inequality

Last registered on June 03, 2026
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Pre-Trial

Trial Information

General Information

Title
Fair versus Unfair Inequality
RCT ID
AEARCTR-0018703
Initial registration date
May 22, 2026

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
June 03, 2026, 7:46 AM EDT

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

Locations

Country
United States of America
Region

Primary Investigator

Name
Jasmin Vietz
Affiliation
University of Hohenheim
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Other Primary Investigator(s)

PI Name
Ingrid Hoem Sjursen
PI Affiliation
Chr. Michelsen Institute
Contact Investigator
PI Name
Nadja Dwenger
PI Affiliation
University of Hohenheim
Contact Investigator

Additional Trial Information

Status
On going
Start date
2026-05-21
End date
2026-06-30
Keywords
Behavior
Additional Keywords
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This pre-analysis plan should be read as an addition to the pre-analysis plans AEARCTR-0010425 and AEARCTR-0016856 submitted to the AEA RCT registry, concerning the same project. The project studies how individuals trade off ensuring fair inequality and avoiding unfair inequality in a spectator design. We collect additional data to elicit participants’ willingness to pay for ensuring fair inequality and for avoiding unfair inequality.
External Link(s)

Registration Citation

Citation
Dwenger, Nadja, Ingrid Hoem Sjursen and Jasmin Vietz. 2026. "Fair versus Unfair Inequality." AEA RCT Registry. June 03. https://doi.org/10.1257/rct.18703-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2026-05-24
Intervention End Date
2026-06-30

Primary Outcomes

Primary Outcomes (end points)
Spectators WTP, elicited via iterative multiple price list
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The experiment is an online experiment with a spectator design on a representative sample of US citizens. There are two types of participants: spectators and workers. Workers complete real effort assignments. Subsequently, spectators make a choice that has monetary consequences for workers.
Experimental Design Details
Not available
Randomization Method
Randomization by survey software
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
Not applicable as no clustering.
Sample size: planned number of observations
400 Spectators
Sample size (or number of clusters) by treatment arms
Participants are randomly assigned to one of two conditions that differ only in question order. In the first condition, participants complete Decision Tree 1 ("costly avoid unfair inequality") followed by Decision Tree 2 ("costly ensure fair inequality"). In the second condition, participants complete the same decision trees in reverse order: Decision Tree 2 first, followed by Decision Tree 1.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials

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IRB

Institutional Review Boards (IRBs)

IRB Name
University of Hohenheim
IRB Approval Date
2026-05-05
IRB Approval Number
2026/27
Analysis Plan