Fair versus Unfair Inequality

Last registered on September 26, 2025

View Trial History

Pre-Trial

Trial Information

General Information

Title

Fair versus Unfair Inequality

RCT ID

AEARCTR-0016856

Initial registration date

September 23, 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

September 26, 2025, 8:33 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

Ingrid Hoem Sjursen

Affiliation

Chr. Michelsen Institute

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

Nadja Dwenger

PI Affiliation

University of Hohenheim

Contact Investigator

PI Name

Jasmin Vietz

PI Affiliation

ifo Institute

Contact Investigator

Additional Trial Information

Status

On going

Start date

2025-09-19

End date

2025-10-31

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 plan AEARCTR-0010425 submitted to the AEA RCT registry, concerning the same project. The project studies how individuals trade of ensuring fair inequality and avoiding unfair inequality in a spectator design. We collect additional data to study how the size of the personal costs for spectators influences their redistributive decision.

External Link(s)

Registration Citation

Citation

Dwenger, Nadja , Ingrid Hoem Sjursen and Jasmin Vietz. 2025. "Fair versus Unfair Inequality." AEA RCT Registry. September 26. https://doi.org/10.1257/rct.16856-1.0

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

We administer an online survey among a representative sample of the US population to elicit individuals’ preferences for reward and equality. We randomize respondents into three treatment groups that vary with respect to the costs of implementing equality and reward: (a) no cost treatment; (b) costly equality treatment; (c) costly reward treatment. We investigate how personal costs for spectators affect their decisions and aim to identify possible tipping points. To do so, we vary the personal costs for spectators in four cost variations within the costly equality and the costly reward treatments.

Intervention (Hidden)

Intervention Start Date

2025-09-19

Intervention End Date

2025-10-31

Primary Outcomes

Primary Outcomes (end points)

The main outcome of interest is the choice of the participant, i.e., whether (s)he redistributes to implement the reward principle or to implement the equality principle.

Primary Outcomes (explanation)

Based on the participants’ decision we will create an indicator that equals one if the participant prefers equality to reward.

Secondary Outcomes

Secondary Outcomes (end points)

Secondary Outcomes (explanation)

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

Randomization Method

Randomization by survey software

Randomization Unit

Individual

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

Not applicable as no clustering.

Sample size: planned number of observations

6,000 Spectators

Sample size (or number of clusters) by treatment arms

Cost variation (1): 500 spectators in control; 500 spectators in treatment 1 (Costly Equality); 500 spectators in treatment 2 (Costly Reward)
Cost variation (2): 500 spectators in control; 500 spectators in treatment 1 (Costly Equality); 500 spectators in treatment 2 (Costly Reward)
Cost variation (3): 500 spectators in control; 500 spectators in treatment 1 (Costly Equality); 500 spectators in treatment 2 (Costly Reward)
Cost variation (4): 500 spectators in control; 500 spectators in treatment 1 (Costly Equality); 500 spectators in treatment 2 (Costly Reward)

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Supporting Documents and Materials

IRB