Default Effects in Web Search

Last registered on February 11, 2025

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Pre-Trial

Trial Information

General Information

Title

Default Effects in Web Search

RCT ID

AEARCTR-0012884

Initial registration date

January 25, 2024

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

January 31, 2024, 1:16 PM EST

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

Last updated

February 11, 2025, 9:01 AM EST

Last updated is the most recent time when changes to the trial's registration were published.

Locations

Country

United States of America

Region

Primary Investigator

Name

Hunt Allcott

Affiliation

Microsoft Research

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

Juan Camilo Castillo

PI Affiliation

University of Pennsylvania

Contact Investigator

PI Name

Matthew Gentzkow

PI Affiliation

Stanford

Contact Investigator

PI Name

Leon Musolff

PI Affiliation

Wharton

Contact Investigator

PI Name

Tobias Salz

PI Affiliation

MIT

Contact Investigator

Additional Trial Information

Status

Completed

Start date

2024-01-23

End date

2024-03-31

Keywords

Other

Additional Keywords

JEL code(s)

Secondary IDs

Prior work

This trial does not extend or rely on any prior RCTs.

Abstract

We cannot risk that participants become aware of this information before the study is complete. Please refer to the pre-analysis plan for more information.

External Link(s)

Registration Citation

Citation

Allcott, Hunt et al. 2025. "Default Effects in Web Search." AEA RCT Registry. February 11. https://doi.org/10.1257/rct.12884-1.2

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

Please refer to the pre-analysis plan for more information.

Intervention (Hidden)

Intervention Start Date

2024-01-23

Intervention End Date

2024-03-31

Primary Outcomes

Primary Outcomes (end points)

We cannot risk that participants become aware of this information before the study is complete. Please refer to the pre-analysis plan for more information.

Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)

Secondary Outcomes (explanation)

Experimental Design

We cannot risk that participants become aware of this information before the study is complete. Please refer to the pre-analysis plan for more information.

Experimental Design Details

We randomize Google and Bing users into different conditions that nudge or incentivize them to search on the other search engine. Please refer to the pre-analysis plan for more information.

Randomization Method

We cannot risk that participants become aware of this information before the study is complete. Please refer to the pre-analysis plan for more information.

Randomization Unit

We cannot risk that participants become aware of this information before the study is complete. Please refer to the pre-analysis plan for more information.

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

We cannot risk that participants become aware of this information before the study is complete. Please refer to the pre-analysis plan for more information.

Sample size: planned number of observations

We cannot risk that participants become aware of this information before the study is complete. Please refer to the pre-analysis plan for more information.

Sample size (or number of clusters) by treatment arms

We cannot risk that participants become aware of this information before the study is complete. Please refer to the pre-analysis plan for more information.

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

Supporting Documents and Materials

IRB