Market Power and Wage Inequality

Last registered on April 29, 2026

Pre-Trial

Trial Information

General Information

Title
Market Power and Wage Inequality
RCT ID
AEARCTR-0018493
Initial registration date
April 26, 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
April 29, 2026, 3:50 PM EDT

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

Locations

Region

Primary Investigator

Affiliation
UC Berkeley

Other Primary Investigator(s)

PI Affiliation
Harvard University

Additional Trial Information

Status
In development
Start date
2026-04-27
End date
2026-08-01
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We survey workers to understand their outside job options and so infer their employers' market power. We then use these answers to estimate a structural model of the labor market.
External Link(s)

Registration Citation

Citation
Noray, Savannah and Wilbur Townsend. 2026. "Market Power and Wage Inequality." AEA RCT Registry. April 29. https://doi.org/10.1257/rct.18493-1.0
Experimental Details

Interventions

Intervention(s)
Intervention (Hidden)
Intervention Start Date
2026-04-27
Intervention End Date
2026-08-01

Primary Outcomes

Primary Outcomes (end points)
There are two outcomes. The first is the respondent’s choice to stay or leave a lower-paying version of their current job. The second is the respondent’s indication that their employer would be willing to give them a pay raise of a certain amount. (See “Experimental Design” for more details)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We plan to use the online survey to collect information on worker rents and rent sharing.
Experimental Design Details
We will sample respondents who are:
+ Living in the U.S.,
+ Ages 22-65,
+ Not a student,
+ College-educated,
+ Fluent in English,
+ Have not done a previous pilot with us,
+ Their main job is a full-time, non-Prolific job where they are
>> Working at least 30 hours per week,
>> Earning at least $10k annually,
>> Either a private sector or government employee (i.e., not self-employed, working without pay for family business/farm, or other type of worker).

The sample will be balanced to be 50% male and 50% female. We will use Prolific’s bot detection and replace individuals in our sample who are detected as bots with new respondents.

WORKER RENTS: We plan to measure worker rents – the amount of wages a worker is willing to forgo in order to stay at their current job – using hypothetical discrete choice experiments (Mas & Pallais, 2017). Specifically, we will ask them both whether they expect to leave their current job within T months, and whether they would expect to leave their current job if it paid X% more or less than it currently does. We will randomize T between {3,6}. Among respondents who currently plan to remain at their current job we will randomize X between {-1,-3,-5,-7,-10,-13,-16,-20,-25}; among respondents who currently plan to leave their current job we will randomize X between {1,3,5,7,10,13,16,20,25}. We will also ask workers for the wage increase/decrease at which they would be indifferent about leaving their current job.

RENT SHARING: We will also use the survey to measure firms’ willingness to increase wages in order to retain workers. Specifically, we will elicit workers’ beliefs about whether their firm would raise their wages by Y%, if doing so was necessary to retain them. Across respondents, we will randomly vary Y from {1,3,5,7,10,13,16,20,25}. We will ask respondents for the maximal pay rise that their employer would give them, in order to retain them.

Other questions in our survey include demographic questions, questions on how their current wage was set, and attention checks.
Randomization Method
Randomization is done by the survey software, Qualtrics.
Randomization Unit
Randomization is at the individual level.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
N/A
Sample size: planned number of observations
Our target sample size is 2000 respondents. However we may sample fewer than 2000 respondents if the Prolific platform provides fewer respondents that meet our criteria.
Sample size (or number of clusters) by treatment arms
For both the question on worker rents and the question on rent sharing, each of the 9 cutoffs will be drawn with equal probability.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB

Institutional Review Boards (IRBs)

IRB Name
Harvard University
IRB Approval Date
2026-04-24
IRB Approval Number
IRB25-0725
Analysis Plan

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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