Public good games and attitudes towards vaccination: group size and safe action

Last registered on October 21, 2021

Pre-Trial

Trial Information

General Information

Title
Public good games and attitudes towards vaccination: group size and safe action
RCT ID
AEARCTR-0008408
Initial registration date
October 20, 2021
Last updated
October 21, 2021, 9:49 AM EDT

Locations

Region

Primary Investigator

Affiliation
University of Siena

Other Primary Investigator(s)

PI Affiliation
University of Siena
PI Affiliation
University of Siena

Additional Trial Information

Status
In development
Start date
2021-10-25
End date
2021-10-31
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We use a randomized online survey experiment to understand how the participation rate in a binary threshold public good game is affected by group size and by a safer option of participating (i.e., participating is always beneficial instead of being risky). After the treatment, we also ask a series of questions related to Covid19 and attitudes toward vaccination to test whether there is correlation between participation to the public good game and vaccination.
A total of 1,500 subjects in Italy will be recruited using a sample provided by a vendor. The subjects are representative of the Italian population for age and geographical location. Subjects are compensated for their participation and are also incentivized in the participation to the games: an additional compensation is provided and depends on the results obtained in the games.
Prior to completing any survey content, respondents will confirm that they are over 18 and located in Italy. If they are not, they are not allowed to continue. Similarly, participants who do not correctly answer a comprehension question about a short newspaper article they are asked to read will not be allowed to continue to the main survey content.
External Link(s)

Registration Citation

Citation
Basili, Marcello, Alessio Muscillo and Paolo Pin. 2021. "Public good games and attitudes towards vaccination: group size and safe action." AEA RCT Registry. October 21. https://doi.org/10.1257/rct.8408-1.0
Experimental Details

Interventions

Intervention(s)
Respondents participate to 3 games: (G1) “risk elicitation game”, (G2) “binary threshold public good game” and (G3) “belief elicitation game about G2”.
The first two treatments consist in randomly grouping the respondents in groups of small size and of large size (5 people or 50 people). The third treatment consists in a modification of the binary threshold public good game in a way such that the “participate” action is always beneficial (instead of being “risky” if the participation threshold is not reached by the group) while keeping the group size as large as in the second treatment.
Intervention Start Date
2021-10-25
Intervention End Date
2021-10-31

Primary Outcomes

Primary Outcomes (end points)
For Game 1, the outcome is the amount invested by the respondent. For Game 2, it is whether the respondent chooses to participate or not. For Game 3, it is the number of others in her group she believes decided to participate in Game 2.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Respondents are asked whether they are vaccinated or not against Covid19 and what were their motivation to do so. They are also asked what their expectations about the situation in Italy in the next future are.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Respondents participate to an online survey. They are first presented some questions about demographics and location. Then, they are asked to play 3 games. The treatment randomly divides respondents in 3 treatments (T1, T2, T3) and intervenes before Game 2, so Game 2 and Game 3 are different across treatments. However, Game 3 is equal for treatment T2 and T3.
Experimental Design Details
Respondents complete a variety of pre-treatment covariates about their age and location.
Then, they are presented 3 games.
The first game is a “risk elicitation” game, where participants are asked to choose the amount of money they want to invest in a risky project (i.e., a project that succeeds 50% of the times).
The second game is a “binary threshold public good game” where the public good is enjoyed by all participants of the group if the participation threshold is reached (3 out of 5 or 25 out of 50, respectively in T1 and T2-T3). The game is of the type “volunteer’s dilemma” or “Kitty Genovese bystander effect”.
Respondents are randomly assigned to one of the following treatments:
1. treatment T1 “small and risky”: participants are told that they will be randomly assigned to a group of 5 people and participate to a public good game, where the public good is obtained if at least 3 out of 5 people decide to participate;
2. treatment T2 “large and risky”: participants are told that they will be randomly assigned to a group of 50 people and participate to a public good game, where the public good is obtained if at least 25 out of 50 people decide to participate;
3. treatment T3 “large and safe”: participants are told that they will be randomly assigned to a group of 50 people and participate to a public good game, where the public good is obtained if at least 3 out of 5 people decide to participate. The difference with the previous treatment is that the “participate” action is always beneficial for the respondent who chooses to participate, even if the threshold is not reached.
The third game consists in asking the participants to guess how many of the others in their group have participated.
Finally, we ask respondents whether they are vaccinated against Covid-19, their attitude towards vaccination and their expectations about how the situation will evolve in Italy.
Randomization Method
Randomization is done in office by a computer.
Randomization Unit
Randomization is at the individual level. Specifically, each individual is randomly assigned to one of the 3 possible treatments (with even probabilities).
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
1,500 individuals representing the Italian population for demographic characteristics and geographical location.
Sample size: planned number of observations
1,500 individuals.
Sample size (or number of clusters) by treatment arms
Individuals are randomly (and evenly) assigned to their treatment, so we expect around 500 individuals in each of the 3 treatments.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials

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IRB

Institutional Review Boards (IRBs)

IRB Name
CAREUS Comitato per la Ricerca Etica nelle Scienze Umane e Sociali
IRB Approval Date
2021-05-13
IRB Approval Number
Parere n. 21/2021

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