An Experimental Study on Platform Steering

Last registered on August 04, 2026
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Pre-Trial

Trial Information

General Information

Title
An Experimental Study on Platform Steering
RCT ID
AEARCTR-0018200
Initial registration date
August 02, 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
August 04, 2026, 10:00 AM EDT

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

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Primary Investigator

Name
Yifei Wang
Affiliation
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Other Primary Investigator(s)

PI Name
Catherine Tucker
PI Affiliation
MIT
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PI Name
Yulin Hao
PI Affiliation
Peking University HSBC Business School
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PI Name
Yan Luo
PI Affiliation
MIT
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Additional Trial Information

Status
In development
Start date
2026-08-12
End date
2026-10-05
Keywords
Firms & Productivity
Additional Keywords
Platform Power, Steering
JEL code(s)
L11, L13, M31
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
The extent to which platforms have power over participants has been a central concern in recent competition policy debates. One key channel through which platforms can exercise such power is platform steering — the ability to shape buyers’ choices among competing sellers on the platform. In this paper, we study the steering power of a digital aggregator.

We partner with a leading bus ticketing aggregator platform in Bangladesh to conduct a large-scale field experiment. Users are randomly assigned to one of four conditions. In the company-specific discount condition, users receive platform-sponsored discounts for tickets for promoted bus companies. In the messaging treatment, users are shown promotional messages featuring specific bus companies, but without any price discounts. In the generic discount condition, users receive a generic platform-sponsored discount that does not reference any specific company. In the generic message condition, users receive a generic promotional message that does not reference any specific company.

We examine the extent to which these platform interventions steer users toward the promoted sellers. We also investigate how the strength of this effect varies with the type of steering (discounting vs. promotional message), user loyalty to the platform, loyalty to individual bus companies, the level of geographic competition in the local bus market, as well as how platform promotions interact with the platform ranking system.
External Link(s)

Registration Citation

Citation
Hao, Yulin et al. 2026. "An Experimental Study on Platform Steering." AEA RCT Registry. August 04. https://doi.org/10.1257/rct.18200-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
The intervention involves sending SMS messages to consumers in the country who have previously booked bus tickets through the platform at least once since 2025. Depending on the treatment condition to which a user is assigned, the SMS either includes a coupon code that waives the platform usage fee or contains a generic promotional message.

Intervention #1
The platform sends users an SMS message that includes a coupon code which, when applied, waives the platform fee for any ticket purchase on the user’s most frequently traveled route.

Intervention #2
The platform sends users an SMS message that includes a coupon code which, when applied, waives the platform fee for ticket purchases with a specific bus company on the user’s most frequently traveled route. The name of the bus company is explicitly mentioned in the message.

Intervention #3
The platform sends users an SMS message encouraging them to book tickets on the platform with a specific bus company when traveling on the user’s most frequently traveled route. The name of the bus company is explicitly mentioned in the message. No coupon code or other discount is provided.

Intervention #4
The platform sends users a generic SMS message encouraging them to book tickets on the platform when traveling on the user’s most frequently traveled route. No coupon code or other discount is provided.
Intervention Start Date
2026-08-12
Intervention End Date
2026-09-02

Primary Outcomes

Primary Outcomes (end points)
Platform usage: the proportion of users who purchase bus tickets via the platform, among all users who purchase bus tickets, within a certain period

Company choice: the proportion of users who purchase the promoted bus companies, including in on- and off-platform purchases, within a certain period

Site visits: the number of pageviews to the website and app of the platform per route, the number of active users who visit the website and app of the platform per route, the number of pageviews and the average enagement time among users who visit the website and app of the platform per route, within a certain period

Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Coupon redemption: the number and proportion of (incremental) purchases that applied the coupon code among purchases from customers who have access to the coupon code. This measure is used to distinguish between two potential mechanisms underlying the effects of platform price promotions. A high redemption rate would indicate that users actively respond to price reductions, consistent with the platform having pricing power. In contrast, if treatment effects on platform usage or product choice occur primarily without coupon redemption, this would suggest that promotional messages operate mainly by attracting user attention rather than through realized price discounts.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We evaluate whether and how different types of platform promotions affect platform usage and users' product choices. Users are randomly assigned to one of four conditions based on their historically most frequently traveled bus route, as identified from their past bookings on the platform. In the company-specific discount condition, users receive platform-sponsored discounts for tickets for promoted bus companies. In the company-specific messaging condition, users are shown promotional messages featuring specific bus companies, but without any price discounts. In the generic discount condition, users receive a generic platform-sponsored discount that does not reference any specific company. In the generic message condition, users receive a generic promotional message that does not reference any specific company.
Experimental Design Details
Not available
Randomization Method
Randomization done in office by a computer
Randomization Unit
Bus route, defined as an unordered pair of cities.
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
88 routes (city pairs)
Sample size: planned number of observations
We plan to send SMS messages to approximately 2009 users per city pair, totally 176,790 users. However, some SMS delivery failures are expected. The final sample will therefore consist of users for whom the platform successfully delivers the SMS message.
Sample size (or number of clusters) by treatment arms
22 routes (city pairs) for each of the four conditions.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Massachusetts Institute of Technology Committee on the Use of Humans and Experimental Subjects
IRB Approval Date
2025-12-05
IRB Approval Number
E-7303
Analysis Plan