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Field
Abstract
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Before
Some studies showed that young people have lower intentions of COVID-19 vaccination than older people. Our previous study found that nudge-based messages providing information on others’ decisions and behaviors could strengthen the vaccination intentions of the older people, but do not have the same effects for the young people (Sasaki, Saito, and Ohtake, 2021). Therefore, as of June 30, 2021, we have not yet found an effective message to encourage the vaccination of the Japanese people other than the older people.
This study again explores nudge-based messages that can encourage COVID-19 vaccination of youth and middle-aged people with low vaccination intentions at baseline. Our preliminary analysis indicates the possibility that the high need for going out and a rise in altruism among younger people may close the gap in vaccination intentions between older and younger people. One foreign study reported that the message, “Full shot reserved for you,” has a large effect in promoting people to receive the seasonal flu vaccine (Milkman et al., 2021). The similar message may be effective for promoting COVID-19 vaccination of people in Japan. Taking the pre-analysis and the foreign study into account, we develop nudge-based messages for the vaccination of youth and middle-aged people in Japan.
We conduct an online survey experiment toward 2,500 respondents of youth and middle-aged people (25-49 years old) residing throughout Japan. In the experiment, we randomly divide the respondents into five groups. We set a hypothetical question to capture their willingness-to pay (WTP) for COVID-19 vaccine, while displaying messages by group. The five groups consist of one control group and four treatment groups, which display nudge-based messages. After the WTP question, we set questions to capture the degrees of respondents’ autonomous decision-making and emotional burden, because it is important from a policy perspective to find out a nudge-based message that can strengthen people’s vaccination intention and at the same time consider their autonomous decision-making and emotional burden. We set another question to capture respondents’ opinions on whether other people should receive the vaccine.
We use the experimental data and estimate the effects of the four nudge-based messages on the respondents’ WTP, autonomy, emotional burden, and opinion on others’ vaccination. We also investigate whether the messages’ effects are heterogeneous by age, gender, and prior vaccination intention.
At the end of the survey, we explain to the respondents that we have conducted a randomized controlled trial in the survey and its content and purpose. We then ask them if they would like to change their choice regarding whether or not to receive the vaccine. We examine for each group how many respondents changed their choice.
References:
- Sasaki, S., Saito, T., and Ohtake, F. 2021. Nudges for COVID-19 voluntary vaccination: How to explain peer information? Osaka University Discussion Papers In Economics And Business, No.2107.
- Milkman, K.L. et al. 2021. A Mega-Study of Text-Based Nudges Encouraging Patients to Get Vaccinated at an Upcoming Doctor’s Appointment. Proceedings of the National Academy of Sciences, 118(20), e2101165118.
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After
Some studies showed that young people have lower intentions of COVID-19 vaccination than older people. Our previous study found that nudge-based messages providing information on others’ decisions and behaviors could strengthen the vaccination intentions of the older people, but do not have the same effects for the young people (Sasaki, Saito, and Ohtake, 2021). Therefore, as of June 30, 2021, we have not yet found an effective message to encourage the vaccination of the Japanese people other than the older people.
This study again explores nudge-based messages that can encourage COVID-19 vaccination of youth and middle-aged people with low vaccination intentions at baseline. Our preliminary analysis indicates the possibility that the high need for going out and a rise in altruism among younger people may close the gap in vaccination intentions between older and younger people. One foreign study reported that the message, “Full shot reserved for you,” has a large effect in promoting people to receive the seasonal flu vaccine (Milkman et al., 2021). The similar message may be effective for promoting COVID-19 vaccination of people in Japan. Taking the pre-analysis and the foreign study into account, we develop nudge-based messages for the vaccination of youth and middle-aged people in Japan.
We conduct an online survey experiment toward 3,500 respondents of youth and middle-aged people (25-49 years old) residing throughout Japan. In the experiment, we randomly divide the respondents into five groups. We set a hypothetical question to capture their willingness-to pay (WTP) for COVID-19 vaccine, while displaying messages by group. The five groups consist of one control group and four treatment groups, which display nudge-based messages. After the WTP question, we set questions to capture the degrees of respondents’ autonomous decision-making and emotional burden, because it is important from a policy perspective to find out a nudge-based message that can strengthen people’s vaccination intention and at the same time consider their autonomous decision-making and emotional burden. We set another question to capture respondents’ opinions on whether other people should receive the vaccine.
We use the experimental data and estimate the effects of the four nudge-based messages on the respondents’ WTP, autonomy, emotional burden, and opinion on others’ vaccination. We also investigate whether the messages’ effects are heterogeneous by age, gender, and prior vaccination intention.
At the end of the survey, we explain to the respondents that we have conducted a randomized controlled trial in the survey and its content and purpose. We then ask them if they would like to change their choice regarding whether or not to receive the vaccine. We examine for each group how many respondents changed their choice.
References:
- Sasaki, S., Saito, T., and Ohtake, F. 2021. Nudges for COVID-19 voluntary vaccination: How to explain peer information? Osaka University Discussion Papers In Economics And Business, No.2107.
- Milkman, K.L. et al. 2021. A Mega-Study of Text-Based Nudges Encouraging Patients to Get Vaccinated at an Upcoming Doctor’s Appointment. Proceedings of the National Academy of Sciences, 118(20), e2101165118.
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Trial Start Date
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Before
June 30, 2021
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After
July 02, 2021
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Last Published
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Before
June 29, 2021 02:23 PM
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After
July 01, 2021 04:28 AM
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Intervention Start Date
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Before
June 30, 2021
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After
July 02, 2021
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Intervention End Date
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Before
July 05, 2021
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After
July 06, 2021
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Experimental Design (Public)
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Before
In June to July 2021, we conduct an online survey experiment with the following details. We recruit totally 2,500 survey respondents of youth and middle-aged people (25-49 years old) residing throughout Japan from response monitors of a survey company. We randomly divide survey respondents into five groups. In the survey, we set a hypothetical question to capture the respondents’ willingness-to pay (WTP) for COVID-19 vaccine, while displaying messages by group. The control group provides an objective explanation of the vaccine. In addition to the explanation, the four treatment groups display nudge-based messages. Before and after the WTP question, we set questions to capture the respondents’ socio-economic attributes, prior vaccination intention, psychological and behavioral economic characteristics, health status, infection prevention attitudes and behaviors, indicators of autonomous decision making and emotional burden, an indicator of respondents’ opinions on other people’s vaccination, and attitudes toward the vaccine. At the end of the survey, we explain to the respondents that we have conducted a randomized controlled trial in the survey and its content and purpose. We then ask them if they would like to change their choice regarding whether or not to receive the vaccine.
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After
In July 2021, we conduct an online survey experiment with the following details. We recruit totally 3,500 survey respondents of youth and middle-aged people (25-49 years old) residing throughout Japan from response monitors of a survey company. We randomly divide survey respondents into five groups. In the survey, we set a hypothetical question to capture the respondents’ willingness-to pay (WTP) for COVID-19 vaccine, while displaying messages by group. The control group provides an objective explanation of the vaccine. In addition to the explanation, the four treatment groups display nudge-based messages. Before and after the WTP question, we set questions to capture the respondents’ socio-economic attributes, prior vaccination intention, psychological and behavioral economic characteristics, health status, infection prevention attitudes and behaviors, indicators of autonomous decision making and emotional burden, an indicator of respondents’ opinions on other people’s vaccination, and attitudes toward the vaccine. At the end of the survey, we explain to the respondents that we have conducted a randomized controlled trial in the survey and its content and purpose. We then ask them if they would like to change their choice regarding whether or not to receive the vaccine.
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Randomization Method
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Before
Stratified randomization by a survey company. The strata are based on age and gender.
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After
Stratified randomization by a survey company. The strata are based on age, gender, and area of residence.
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Planned Number of Observations
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Before
2,500 individuals
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After
3,500 individuals (at maximum)
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Sample size (or number of clusters) by treatment arms
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Before
500 individuals in the control group, 500 individuals in the treatment group A, 500 individuals in the treatment group B, 500 individuals in the treatment group C, and 500 individuals in the treatment group D.
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After
700 individuals in the control group, 700 individuals in the treatment group A, 700 individuals in the treatment group B, 700 individuals in the treatment group C, and 700 individuals in the treatment group D (at maximum, respectively).
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Pi as first author
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Before
No
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After
Yes
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