Self-Preferencing and Consumer Welfare: Evidence from a Field Experiment

Last registered on June 23, 2023
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Pre-Trial

Trial Information

General Information

Title
Self-Preferencing and Consumer Welfare: Evidence from a Field Experiment
RCT ID
AEARCTR-0011370
Initial registration date
June 13, 2023

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 23, 2023, 4:39 PM 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
Andrey Fradkin
Affiliation
Boston University
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Other Primary Investigator(s)

PI Name
Chiara Farronato
PI Affiliation
Harvard Business School
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PI Name
Alexander MacKay
PI Affiliation
Harvard Business School
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Additional Trial Information

Status
In development
Start date
2023-06-13
End date
2023-10-31
Keywords
Behavior, Firms & Productivity, Welfare
Additional Keywords
digital platforms, self-preferencing, industrial organization, algorithms
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We seek to study how self-preferencing by digital platforms affects consumer welfare and competition.
External Link(s)

Registration Citation

Citation
Farronato, Chiara , Andrey Fradkin and Alexander MacKay. 2023. "Self-Preferencing and Consumer Welfare: Evidence from a Field Experiment." AEA RCT Registry. June 23. https://doi.org/10.1257/rct.11370-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
Group 1 is the control group, for which the extension simply monitors participants' behavior. The extension tracks browsing behaviors on Amazon.com, ensuring that confidential information is removed before storing the data. Additionally, the extension tracks URLs visited on other major e-commerce websites, but it does not collect more detailed tracking data or intervene with what the participants see on these websites.
Group 2 is the Amazon treatment group. For this group, the extension hides major Amazon-owned brands from the participants' browsing experience on Amazon.com. This mainly includes removing Amazon-branded products from search and product pages.
Group 3 is the random treatment group. This group is similar to group 2, except that instead of hiding the Amazon-branded products from a web page, the extension hides a random set of products, where the number of hidden products is equal to the number of Amazon-branded products on that web page.

See the included document for details.
Intervention Start Date
2023-06-13
Intervention End Date
2023-10-31

Primary Outcomes

Primary Outcomes (end points)
See the pre-registration document and analysis plan.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
See the pre-registration document and analysis plan.
Experimental Design Details
Randomization Method
Simple randomization by computer
Randomization Unit
The unit of randomization is the study participant.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
1200 participants, with 1000 minimum if costs of recruitment increase substantially
Sample size: planned number of observations
1200 participants, 6 wishlist task choices per participant
Sample size (or number of clusters) by treatment arms
400 control, 400 amazon brands hide, 400 random hide
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
Harvard University Institutional Review Board
IRB Approval Date
2023-06-12
IRB Approval Number
MOD21-1677-11
Analysis Plan

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