Listen to me, I will respond”: a randomized communication trial on vaccination decisions

Last registered on March 05, 2025
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Pre-Trial

Trial Information

General Information

Title
Listen to me, I will respond”: a randomized communication trial on vaccination decisions
RCT ID
AEARCTR-0011862
Initial registration date
July 31, 2023

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
August 09, 2023, 2:48 PM EDT

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

Last updated
March 05, 2025, 9:28 AM EST

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

Locations

Country
Italy
Region
all

Primary Investigator

Name
Alice Dominici
Affiliation
European University Institute, Department of Economics/Karolinska Institute, Department of Medical Epidemiology and Biostatistics
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Other Primary Investigator(s)

PI Name
Leonardo Boncinelli
PI Affiliation
University of Florence
Contact Investigator
PI Name
Ennio Bilancini
PI Affiliation
IMT Lucca
Contact Investigator
PI Name
Folco Panizza
PI Affiliation
IMT Lucca
Contact Investigator

Additional Trial Information

Status
Completed
Start date
2023-09-15
End date
2024-07-31
Keywords
Health
Additional Keywords
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We study whether motivational interviewing, a technique used in clinical dialogues, can foster vaccination uptake when applied in video informational campaigns. We investigate its interaction with more common nudges in a factorial design.
External Link(s)

Registration Citation

Citation
Bilancini, Ennio et al. 2025. "Listen to me, I will respond”: a randomized communication trial on vaccination decisions." AEA RCT Registry. March 05. https://doi.org/10.1257/rct.11862-2.1
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
Intervention (Hidden)
Informational videos (approximately 1.40 minutes each) about the dangers of not vaccinating against the flu and other information about the flu vaccine. Across different treatment groups, they vary along all 3 combinations of the following dimensions:

1) Whether the information is given by a single person with direct and paternalistic communication (mirroring techniques used by Italian health authorities in existing video campaigns on vaccines) or by two people who have a dialogue based on Motivational Interviewing (technique developed and tested by psychologists to convince hesitant patients in 1-to-1 interactions with doctors, and recommended by the WHO)

2) The gender of the informant in the video

3) Whether the informant is presented as a medical doctor (wearing a doctor's coat) or not

4) Gender concordance between the informed person in the dialogue video and the receiver, and with the informant

Intervention Start Date
2023-09-15
Intervention End Date
2024-02-01

Primary Outcomes

Primary Outcomes (end points)
Self-reported intention to vaccinate right after treatment
Self-reported vaccination status against the flu 3-4 months after treatment
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Listed in pre-analysis plan and visible in the attached surveys
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Factorial: the combination of all 4 treatment creates 16 cells. For each one, we will invite approximately 500 subjects who will see the video and participate through an online survey.
Experimental Design Details
Randomization Method
Performed by the survey software upon connection
Randomization Unit
Individuals
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
None
Sample size: planned number of observations
12000
Sample size (or number of clusters) by treatment arms
500 in each of the 16 cells (the difference between the resulting sample size of 8000 and the overall planned number of observation of 12000 - the invitees) is to account for partial response rate.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Included in the attached pre-analysis plan
Supporting Documents and Materials

Documents

Document Name
Surveys
Document Type
survey_instrument
Document Description
Rough translation (from Italian to English) of the survey instruments used to measure baseline covariates, administer treatment interventions, and measure outcomes.
File
Surveys

MD5: e26163bf107b37e2a14ce9cae047e4e9

SHA1: e8a9b48b81225db5268bcd58df14f16f65632930

Uploaded At: August 10, 2023

IRB

Institutional Review Boards (IRBs)

IRB Name
European University Institute's Ethics Committee
IRB Approval Date
2023-07-28
IRB Approval Number
20220906_DOMINICI AMEND 1
Analysis Plan

Analysis Plan Documents

Pre-Analysis Plan Dominici et al 2024 The limits and perils of gentle communication

MD5: 17dfc0a6fdf95a8baf3dc47a0d0aec84

SHA1: 7b94e43dbecb0e68814b224a3f1f21bb7dc3f0bf

Uploaded At: August 10, 2023

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