Demand for Anti-Trust: An Experimental Investigation

Last registered on May 11, 2026

Pre-Trial

Trial Information

General Information

Title
Demand for Anti-Trust: An Experimental Investigation
RCT ID
AEARCTR-0018249
Initial registration date
May 04, 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
May 11, 2026, 8:09 AM EDT

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

Locations

Region

Primary Investigator

Affiliation
UCLA

Other Primary Investigator(s)

PI Affiliation
University of Stuttgart

Additional Trial Information

Status
In development
Start date
2026-05-04
End date
2026-12-31
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We designed a survey experiment to examine the determinants of demand for antitrust enforcement among U.S. respondents. Participants are randomly assigned to one of five recent antitrust cases involving Google, Luxottica, Apple, Live Nation, or Meta. Within each case, participants are further randomized to one of five treatment groups: a control group that receives no additional information and four treatment groups that receive different information messages about the case. The experiment is designed to measure how exposure to different types of information affects respondents’ support for antitrust enforcement.
External Link(s)

Registration Citation

Citation
Perez-Truglia, Ricardo and Jeffrey Yusof. 2026. "Demand for Anti-Trust: An Experimental Investigation." AEA RCT Registry. May 11. https://doi.org/10.1257/rct.18249-1.0
Experimental Details

Interventions

Intervention(s)
Participants in a U.S.-based survey are randomly assigned to one of five recent antitrust cases involving Google, Luxottica, Apple, Live Nation, or Meta. Within each case, participants are further randomized to either a control condition, in which they receive no additional information, or to one of four treatment conditions, each of which provides different information about the case. We measure effects on beliefs and preferences in the baseline survey and again in a follow-up survey to be conducted one month later.
Intervention Start Date
2026-05-04
Intervention End Date
2026-12-31

Primary Outcomes

Primary Outcomes (end points)
The full survey instruments for both the baseline and follow-up surveys are attached to this application. The primary outcome is respondents’ preferences for antitrust enforcement. This outcome is measured first using a support scale capturing respondents’ level of support for the specific antitrust action in the case to which they are assigned. We also collect alternative and complementary outcome measures.
Primary Outcomes (explanation)
As shown in the survey instrument, the alternative and complementary outcome measures include respondents’ support for remedies regarding the case they were assigned to (e.g., break down the company), general antitrust policy proposals, donations to a pro-antitrust nonprofit, willingness to sign an antitrust petition, willingness to write an email to a representative in support of stronger antitrust enforcement, and a willingness-to-pay measure capturing whether they like the company.
To improve the precision of the estimates, in addition to estimating effects on specific outcomes, we will also construct an index for each outcome category.

Secondary Outcomes

Secondary Outcomes (end points)
To shed light on the underlying mechanisms, the survey elicits both prior and posterior beliefs about four objects: the company’s perceived market share, the fairness of competition in the relevant market, the extent of consumer harm, and the respondent’s overall perception of the company. In addition to company-specific posterior beliefs, we include similar questions to measure posterior beliefs about dominant companies in general. The follow-up survey also asks respondents to represent the government side (for example, the DOJ) in a debate against an AI lawyer representing the company. This exercise allows us to measure whether the treatment affects the types of arguments respondents use as well as the overall persuasiveness of those arguments.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Participants are randomly assigned to one of five recent antitrust cases involving Google, Luxottica, Apple, Live Nation, or Meta. Within each case, participants are further randomized to either a control condition, in which they receive no additional information, or to one of four treatment conditions, each of which provides different information about the case. We measure effects on beliefs and preferences in the baseline survey and again in a follow-up survey to be conducted one month later.
Experimental Design Details
Not available
Randomization Method
Randomization is implemented automatically by the survey software Qualtrics at the individual respondent level.
Randomization Unit
Individual respondent
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
4,000 respondents
Sample size: planned number of observations
4,000 respondents
Sample size (or number of clusters) by treatment arms
The 4,000 respondents are first randomly assigned, with equal probability, to one of five antitrust cases.
These same respondents are then randomly assigned, with equal probability, to one of the five treatment groups.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials

Documents

Document Name
Follow-Up Survey
Document Type
survey_instrument
Document Description
File
Follow-Up Survey

MD5: 03310f4dbba8797a0afd6284ae3c169f

SHA1: f11e15fd36b57a7be554f42d9a1ec307df3ba0e2

Uploaded At: April 29, 2026

Document Name
Baseline Survey
Document Type
survey_instrument
Document Description
File
Baseline Survey

MD5: 34d8de64ca66191eed8974f08066f528

SHA1: 8121774952f9606b276334d733ec385068e095bf

Uploaded At: May 04, 2026

IRB

Institutional Review Boards (IRBs)

IRB Name
North General Institutional Review Board at University of California, Los Angeles
IRB Approval Date
2026-04-02
IRB Approval Number
IRB-26-0751