Incentives, economic preferences and vaccination uptake

Last registered on August 26, 2024
View Trial History

Pre-Trial

Trial Information

General Information

Title
Incentives, economic preferences and vaccination uptake
RCT ID
AEARCTR-0008906
Initial registration date
January 27, 2022

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
January 27, 2022, 1:10 PM EST

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

Last updated
August 26, 2024, 2:57 PM EDT

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

Locations

Country
Sweden
Region

Primary Investigator

Name
Florian Schneider
Affiliation
University of Zurich
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
Pol Campos-Mercade
PI Affiliation
PI Name
Armando Meier
PI Affiliation
PI Name
Stephan Meier
PI Affiliation
PI Name
Devin Pope
PI Affiliation
PI Name
Erik Wengström
PI Affiliation

Additional Trial Information

Status
Completed
Start date
2022-01-27
End date
2023-12-31
Keywords
Behavior, Health
Additional Keywords
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We study the impact of different incentive schemes on COVID-19 booster shot uptake in Sweden. We look at actual vaccination behavior and vaccination intentions.
External Link(s)

Registration Citation

Citation
Campos-Mercade, Pol et al. 2024. "Incentives, economic preferences and vaccination uptake." AEA RCT Registry. August 26. https://doi.org/10.1257/rct.8906-1.1
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2022-01-27
Intervention End Date
2022-02-28

Primary Outcomes

Primary Outcomes (end points)
Vaccination uptake: Did the participant get a third shot (booster shot) of a COVID-19 vaccine within the first month of trial participation? (0/1)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
To address our research questions, we conduct a survey with a general population sample of the Swedish population.We randomly allocate participants to an intervention. Next, we measure participants' intentions to get vaccinated. Last, we examine whether people did or did not get a booster shot (third dose) using data from administrative registers.
Experimental Design Details
To address our research questions, we conduct a survey with a general population sample of the Swedish population. In the online survey, we first measure participants’ preferences. Then we randomly allocate participants to an intervention. Next, we measure participants' intentions to get vaccinated. Last, we examine whether people did or did not get a booster shot (third dose) using data from administrative registers.

First, we measure participants’ economic preferences, in particular altruism and risk preferences (see pre-analysis plan for details).

Then, we randomly allocate participants to one of five conditions. First, we have a control condition:

• Control condition: We encourage participants to take the third dose of a COVID-19 vaccine.

Second, we study the impact of four incentive schemes which all have an expected payoff of SEK 200. All schemes include the same encouragement as in the control condition plus the treatment:

• Guaranteed payment: We offer people SEK 200 if they get vaccinated within 1 month, which we check using administrative data.
• Lottery incentive: We offer people a lottery ticket with a 1% chance of winning SEK 20,000 (expected value is SEK 200) if they get vaccinated within 1 month, which we check using administrative data.
• Prosocial incentive: We offer people a donation of SEK 200 to the charity Save the Children if they get vaccinated within 1 month, which we check using administrative data.
• Choice of incentive: We offer people the free choice of any of the three incentive schemes (guaranteed payment, lottery or prosocial incentive). We pay people the chosen incentive if they get vaccinated within 1 month, which we check using administrative data.

Next, we ask participants about their intentions to receive the COVID-19 vaccine.

We will be able to match our survey responses with administrative data on vaccination uptake. For all participants we will see whether and when they received the third dose of a COVID-19 vaccine.
Randomization Method
Randomization is done by a computer
Randomization Unit
We randomize at the individual level.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
We aim to collect data from about 6,000 participants. However, there is some uncertainty about the number of people that can be recruited, and we could end up with a higher or small sample size. Importantly, we will not have access to the vaccination data until we have finished data collection.
Sample size: planned number of observations
We aim to collect data from about 6,000 participants. However, there is some uncertainty about the number of people that can be recruited, and we could end up with a higher or small sample size. Importantly, we will not have access to the vaccination data until we have finished data collection.
Sample size (or number of clusters) by treatment arms
We have a total of five conditions. We allocate 1/5 of the sample size to each condition.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
With 6’000 observations and using a baseline in which 60% of the participants in the control group vaccinate, we will have 80% power to detect an effect size of about 5 percentage points.
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Etikprövningsmyndigheten Sweden
IRB Approval Date
2022-01-17
IRB Approval Number
2021-06669-01
Analysis Plan

Analysis Plan Documents

PreAnalysisPlan_v13.pdf

MD5: 0c5fad2ac3d876903b7a94109fd83142

SHA1: cca5cc983f12f0143d16ae0e895678061607486f

Uploaded At: January 27, 2022

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
Data Collection Complete
Yes
Data Collection Completion Date
Final Sample Size: Number of Clusters (Unit of Randomization)
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
Final Sample Size (or Number of Clusters) by Treatment Arms
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials