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Situation-dependent willingness to pay for the Covid-19 vaccine: Infection stage, peers, and nudges
Last registered on January 19, 2021

Pre-Trial

Trial Information
General Information
Title
Situation-dependent willingness to pay for the Covid-19 vaccine: Infection stage, peers, and nudges
RCT ID
AEARCTR-0007056
Initial registration date
January 15, 2021
Last updated
January 19, 2021 8:55 PM EST
Location(s)
Region
Primary Investigator
Affiliation
Tohoku Gakuin University
Other Primary Investigator(s)
PI Affiliation
Osaka University
PI Affiliation
National Institute of Infectious Diseases
Additional Trial Information
Status
On going
Start date
2021-01-18
End date
2022-03-31
Secondary IDs
Abstract
We study the levels and characteristics of people's willingness-to-pays (WTPs) for the Covid-19 vaccine under various situations, by conducting a survey experiment on a nationwide sample in Japan and using multiple hypothetical questions with Multiple Price List formats. Specifically, we conduct the following three studies. In Study 1, we examine how the levels of the WTPs change according to vaccine effectiveness, infection stage, and vaccination progress. We then conduct a follow-up survey, capture their actual vaccination behavior, and clarify the correlation between their WTPs and vaccination behavior. In Study 2, we examine how the WTPs are influenced by nudge-based messages emphasizing selfish or altruistic benefits of the vaccination. In Study 3, we compare the levels and characteristics of the WTPs between young people (25-39 years old) and elderly people (60-74 years old). We further explore how the WTPs’ differences depend on the distributions and parameters of the variables of socio-economic attributes and behavioral economic and psychological characteristics, including time preferences, risk preferences, social preferences, and subjective risks.
External Link(s)
Registration Citation
Citation
Sasaki, Shusaku, Fumio Ohtake and Tomoya Saito. 2021. "Situation-dependent willingness to pay for the Covid-19 vaccine: Infection stage, peers, and nudges." AEA RCT Registry. January 19. https://doi.org/10.1257/rct.7056-1.1.
Experimental Details
Interventions
Intervention(s)
We conduct an online survey experiment and randomly assign the survey respondents to either of one control group and two treatment groups. One treatment group provides a message emphasizing selfish benefits of vaccination, while another treatment group provides a message emphasizing its social (altruistic) benefits.
Intervention Start Date
2021-01-18
Intervention End Date
2021-01-20
Primary Outcomes
Primary Outcomes (end points)
Willingness to pay for the Covid-19 vaccine (in the initial main survey)
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Willingness to pay and self-reported vaccination behavior (in the follow-up surveys)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
We conduct an online survey experiment and randomly assign the survey respondents to either of one control group and two treatment groups. One treatment group provides a message emphasizing selfish benefits of vaccination, while another treatment group provides a message emphasizing its social (altruistic) benefits.
Experimental Design Details
Not available
Randomization Method
Stratified randomization by a survey company. The strata are based on age, gender, and place of residence.
Randomization Unit
Individuals
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
N/A
Sample size: planned number of observations
12,000 individuals (at maximum)
Sample size (or number of clusters) by treatment arms
6,000 individuals in the control group, 3,000 individuals in the selfish-message group, and 3,000 individuals in the altruistic-message group (respectively at maximum)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
Graduate School of Economics, Osaka University IRB
IRB Approval Date
2021-01-04
IRB Approval Number
N/A