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Self-selective Belief Updating: A Survey Experiment on COVID-19 Vaccine Information

Last registered on November 09, 2021
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Pre-Trial

Trial Information

General Information

Title
Self-selective Belief Updating: A Survey Experiment on COVID-19 Vaccine Information
RCT ID
AEARCTR-0008272
Initial registration date
October 26, 2021

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
October 27, 2021, 10:39 PM EDT

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

Last updated
November 09, 2021, 4:39 AM EST

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

Locations

Country
Taiwan, Province of China
Region

Primary Investigator

Name
ChienHsun Lin
Affiliation
UCSB
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
Hans Hanpu Tung
PI Affiliation
National Taiwan University
Contact Investigator

Additional Trial Information

Status
In development
Start date
2021-11-08
End date
2021-11-20
Keywords
Behavior, Health
Additional Keywords
Media, Information
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We conduct an online survey experiment providing information about vaccines from different manufacturers of COVID-19 to subjects below 20 years old in Taiwan. We provide the subjects information sheets about the vaccines from different manufacturers, which include information such as efficacy, safety, and the platform that the vaccines use. Then we see how the subjects update their beliefs about the vaccines and how their preferences on different vaccines change. In order to identify the effect in belief updating of following two factors (1) the self-selection in consumption of information and (2) the motivated updating from information, we designed 3 treatments: (A) allowing subject to freely choose which and how many information sheet to read, (B) allow subjects to choose a fixed amount of information to read, and (C) assign a fixed amount of information sheets for subjects to read.
External Link(s)

Registration Citation

Citation
Lin, ChienHsun and Hans Hanpu Tung. 2021. "Self-selective Belief Updating: A Survey Experiment on COVID-19 Vaccine Information." AEA RCT Registry. November 09. https://doi.org/10.1257/rct.8272-2.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
Intervention (Hidden)
Intervention Start Date
2021-11-08
Intervention End Date
2021-11-20

Primary Outcomes

Primary Outcomes (end points)
The change in beliefs on different attributes of vaccines, including: efficacy, hospitalization prevention rates, and adverse event rates.
Primary Outcomes (explanation)
We survey the subjects about their beliefs on the attributes of different vaccines before and after the intervention. In the intervention, or the "information sheets", these attributes are provided. We also defined these terms to eliminate potential misunderstanding.

Secondary Outcomes

Secondary Outcomes (end points)
The change in preferences to different vaccines.
Secondary Outcomes (explanation)
We evaluate the preferences by directly asking the degree of preference and by the willingness to wait for a full vaccine shot.

Experimental Design

Experimental Design
We provide the information about the vaccines collected from WHO and peer-reviewed scientific reports. In the experiment, we provide subjects the information sheets, and they declare their beliefs about the attributes and preferences about vaccines.
Experimental Design Details
In the experiment, we have three main treatment arms.
(1) Free Choice
In this treatment arm, the subjects can freely choice 0-3 out of 5 information sheets about vaccines to read.
(2) Top 3 Choice
In this treatment arm, the subjects can choice the top 3 out of 5 information sheets about vaccines to read.
(3) Assigned
In this treatment arm, the subjects are assigned 3 out of 5 information sheets about vaccines to read.

Before the information, we let all subjects in the above three treatment arms rank the 5 treatment sheets and choose the amount of sheets to read. In order to eliminate possible bias from using the strategic methods, we add 2 more arms as robustness check.
(2*) Top 3 Choice - No Amounts
In this treatment arm, the subjects can choice the top 3 out of 5 information sheets about vaccines to read, while they are not asked of the number of the sheets they want to read.
(3*) Assigned - No Ranking
In this treatment arm, the subjects are assigned 3 out of 5 information sheets about vaccines to read, while they are neither asked of the ranking among sheets nor asked of the amount of sheets they want to read.
Randomization Method
Randomization done by the survey platform (Qualtrics).
Randomization Unit
individual.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
1100 individuals.
Sample size: planned number of observations
1100 individuals.
Sample size (or number of clusters) by treatment arms
300 free-choices
300 top 3-choices
300 assigned
100 top 3-choices without asking amounts
100 assigned without asking rankings
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Research Ethics Committee, National Taiwan University
IRB Approval Date
2021-03-15
IRB Approval Number
202102HS016
IRB Name
Human Subjects Committee, Office of Research, University of California, Santa Barbara
IRB Approval Date
2021-09-03
IRB Approval Number
23-21-0388
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
Yes
Intervention Completion Date
November 16, 2021, 12:00 +00:00
Data Collection Complete
Yes
Data Collection Completion Date
November 16, 2021, 12:00 +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
1066 subjects
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
1066 subjects
Final Sample Size (or Number of Clusters) by Treatment Arms
176 full compliance, 167 top 3 choice, 289 random assign, 233 top 3 choice (no select), 201 assigned (no rank)
Data Publication

Data Publication

Is public data available?
No

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Program Files

Program Files
No
Reports, Papers & Other Materials

Relevant Paper(s)

Abstract
Rational information acquisition theory predicts people select the information that is more informative, thus people's beliefs will be more persuaded by the information they select. We test the prediction in a critical real-world context---information about COVID-19 vaccines. We conduct an online experiment in Taiwan where the subjects select information about COVID-19 vaccines, and then the subjects update their beliefs about the vaccine effectiveness and preferences of vaccines. As our design distinguishes different stages of the rational acquisition framework, it allows us to diagnose the underlying mechanism of the theory. Our empirical findings demonstrate evidence that people's information acquisition generally coheres with the rational theory framework predictions, that is, people choose information when the information is more likely to alter their decisions.
We show that our subjects' beliefs change more when they see the information they select. We also find evidence of change in vaccine choices after they receive the information they select, which further suggests that the subjects follow the rational information acquisition framework.
Citation
Lin, ChienHsun, Hans H. Tung. (2023) The self-selection of information and the belief update: An experiment on COVID-19 vaccine information. Working paper.
URL
https://drive.google.com/file/d/1Yb-T3oiCFqtyMf-BQaj4aqvVkXkfqH2p/view?usp=sharing

Reports & Other Materials