Social Norms for COVID-19 Vaccination

Last registered on June 11, 2021
View Trial History

Pre-Trial

Trial Information

General Information

Title
Social Norms for COVID-19 Vaccination
RCT ID
AEARCTR-0007634
Initial registration date
May 05, 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
May 06, 2021, 6:18 AM EDT

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

Last updated
June 11, 2021, 12:09 PM EDT

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

Locations

Country
United States of America
Region
Montana

Primary Investigator

Name
Mariana Carrera
Affiliation
Montana State University
Contact Primary Investigator

Other Primary Investigator(s)

Additional Trial Information

Status
On going
Start date
2021-05-05
End date
2021-08-31
Keywords
Behavior, Health
Additional Keywords
vaccination, social norms
JEL code(s)
Secondary IDs
Abstract
This study uses a survey-based experiment to test how the provision of descriptive social norm information, namely, the share of other study participants who intend to receive COVID-19 vaccinations, influences a student's perceptions of COVID-19 and stated intention of vaccination.
External Link(s)

Registration Citation

Citation
Carrera, Mariana. 2021. "Social Norms for COVID-19 Vaccination." AEA RCT Registry. June 11. https://doi.org/10.1257/rct.7634-1.2000000000000002
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
A randomized information treatment presents the share of participants from an earlier survey wave who answered that they are already vaccinated or intend to receive their COVID-19 vaccination by June 30, 2021.
Intervention Start Date
2021-05-05
Intervention End Date
2021-06-30

Primary Outcomes

Primary Outcomes (end points)
Stated intention to vaccinate against COVID-19, Subjective probability of vaccination by June 30, Estimated percent of students at same university who will be fully vaccinated at the start of fall semester, and Expected number of cases of COVID-19 at the university in Fall 2021.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Perceptions of risks of COVID-19 vaccines, Vaccination by June 30 if not yet vaccinated at time of survey, Clicking on links offered to learn more about COVID vaccination and COVID infection or to schedule an appointment for vaccination.
Secondary Outcomes (explanation)
A number of questions regarding COVID-19 vaccination risks and side effects will be normalized and averaged for this secondary outcome. For a subset of consented participants, vaccination records will be searched through the state registry.

Experimental Design

Experimental Design
In this survey-based experiment, students are first asked to guess the share of participants who have been, or intend to be, vaccinated against COVID-19. They are then randomized into an information treatment and control group. The information treatment group sees information on the responses of past participants. Then, all participants are asked to state whether they intend to be vaccinated against COVID-19, have already been vaccinated, are undecided, or are not interested in vaccinated.
Experimental Design Details
In this survey-based experiment, students are first asked to guess the share of participants who have been, or intend to be, vaccinated against COVID-19. They are then randomized into an information treatment and control group. The information treatment group sees information on the responses of past participants. Then, all participants are asked to state whether they intend to be vaccinated against COVID-19, have already been vaccinated, are undecided, or are not interested in vaccinated.

In addition, participants must take a photo of themselves that may be shared, along with their vaccination intention, with other participants. Participants are randomized into two groups: In one group, students state their preference for sharing or not sharing their photo and vaccination intention with other participants, and then complete an incentive-compatible multiple price list where they indicate whether they prefer to share or not share under various possible incentives to share or not share. In the second group, students are told they have been selected to have their photos shared, but they have the option to change the vaccination statement that appears beneath it. The selected photos and statements are added to the information treatment seen by approximately half of participants in the first part of the survey.

The information treatment is also divided into sub-treatments showing different percentage values of students vaccinated based on the responses calculated in different waves of the survey.
Randomization Method
Qualtrics block randomization
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
1 school
Sample size: planned number of observations
500-1000 students
Sample size (or number of clusters) by treatment arms
One half receiving information treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Montana State University
IRB Approval Date
2021-05-03
IRB Approval Number
MC050321-FC
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