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Influence of social norms on attitudes towards COVID-19 vaccination
Last registered on April 06, 2021

Pre-Trial

Trial Information
General Information
Title
Influence of social norms on attitudes towards COVID-19 vaccination
RCT ID
AEARCTR-0007457
Initial registration date
April 05, 2021
Last updated
April 06, 2021 6:41 AM EDT
Location(s)

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Primary Investigator
Affiliation
University of Innsbruck
Other Primary Investigator(s)
PI Affiliation
ifo Center for the Economics of Education
PI Affiliation
UMIT Tirol
PI Affiliation
University of Innsbruck
Additional Trial Information
Status
In development
Start date
2021-04-09
End date
2022-12-31
Secondary IDs
Abstract
Despite the immense utility that anti-COVID-19 vaccines create for individuals and society at large, recent surveys show that about 25 to 42 percent of Germans do not intend to vaccinate against COVID-19. However, high uptake rates are crucial for achieving herd immunity. We investigate the extent to which individual vaccination intentions are affected by information about the social norm towards vaccination. In particular, we plan do conduct a representative survey in Germany that elicits respondents’ beliefs about the social norm regarding anti-COVID-19 vaccination. We then experimentally correctly potentially biased beliefs through factual information provision, and investigate how this affects attitudes towards anti-COVID-19 vaccination.
External Link(s)
Registration Citation
Citation
Angerer, Silvia et al. 2021. "Influence of social norms on attitudes towards COVID-19 vaccination ." AEA RCT Registry. April 06. https://doi.org/10.1257/rct.7457-3.0.
Sponsors & Partners

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Experimental Details
Interventions
Intervention(s)
We investigate whether providing citizens with representative information about the vaccination intentions of adults in Germany affects their intention to get the COVID-19-vaccine. Therefore, we plan to run an information provision experiment, where we provide respondents with information about social norms.
After eliciting beliefs about the social norm, we provide one group of participants with information about the norm, elicited in a prior survey, while the control group gets no additional information. Afterward we ask several questions concerning the respondents readiness to get vaccinated against COVID-19 as well as other vaccine-related questions.
Intervention Start Date
2021-04-09
Intervention End Date
2021-05-20
Primary Outcomes
Primary Outcomes (end points)
Intention to get vaccinated (5 outcomes), willingness to pay for the vaccine (2 outcomes), and normative social norm (2 outcomes). In our main analysis, we will create summary indices of these outcomes and estimate treatment effects on these indices. We will also investigate treatment effects on individual outcomes.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Heterogeneity by prior beliefs; treatment effects on mediators and moderators (Q8 and Q9).
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
We plan to sample a minimum of 2,000 adults aged between 18 and 69 years (up to a maximum of 3,000 — conditional on pending supplementary research funding; also see “Experiment characteristics”).
The survey is conducted in cooperation with a survey institute. The recruitment and polling are managed by the survey institute, which collects the data via an online platform. That is, our participants answer the survey questions autonomously on their own digital devices. Randomization is carried out by the survey institute at the individual level, using a computer.
Our experiment is structured as follows:
Respondents will be randomly assigned (between subject) to
Treatment 1 (p=0.5), or Treatment 2 (p=0.5).

Treatment 1:
Stage 1: Beliefs about social norms
[no Information-provision]
Stage 2: Intention to vaccinate — Index
Stage 3: Moderators and Mediators
Stage 4: Personal Questions & Time-, risk-, and social preferences


Treatment 2:
Stage 1: Beliefs about social norms
[Information about descriptive norm]
Stage 2: Intention to vaccinate — Index [+ info: descriptive norm]
Stage 3: Moderators and Mediators [+ info: descriptive norm]
Stage 4: Personal Questions & Time-, risk-, and social preferences
Experimental Design Details
Not available
Randomization Method
(e.g. public lottery, randomization done in office by a computer, coin flip): Randomization is carried out by the survey company, using a computer.
Randomization Unit
at the individual level
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
2,000 individuals (adults aged between 18 and 69 years). (maximum: 3,000 – conditional on pending supplementary research funding)
Sample size: planned number of observations
2,000 individuals (1,000 per treatment). (maximum: 3,000 (1,500/1,500) – conditional on pending supplementary research funding). According to our conservative cost calculations, we have sufficient funding for sampling 2,000 individuals. In case that we are granted supplementary research funding, we envisage to continue sampling up to a maximum number of 3,000 individuals.
Sample size (or number of clusters) by treatment arms
1,000 per treatment (maximum 1,500/1,500 - conditional on pending supplementary research funding)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
Ludwig-Maximilians-Universität München, Volkswirtschaftliche Fakultät, Ethikkommission
IRB Approval Date
2021-03-03
IRB Approval Number
Project 2021-06