Evaluating the Effects of Nudge Messages to Promote Early Evacuation

Last registered on July 13, 2022

Pre-Trial

Trial Information

General Information

Title
Evaluating the Effects of Nudge Messages to Promote Early Evacuation
RCT ID
AEARCTR-0009629
Initial registration date
June 23, 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
June 26, 2022, 5:23 AM EDT

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

Last updated
July 13, 2022, 6:36 AM EDT

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

Locations

Region

Primary Investigator

Affiliation
Osaka University

Other Primary Investigator(s)

PI Affiliation
Osaka University

Additional Trial Information

Status
Completed
Start date
2022-06-22
End date
2022-06-27
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
In this study, we will evaluate the effects of nudge messages to promote early evacuation before heavy rains occur. To examine the effects, we are going to conduct two online questionnaire RCT surveys. In the first survey, we will provide nudge messages to promote early evacuation and ask the willingness to evacuate under a hypothetical heavy rain situation. We are going to conduct follow-up survey two month later and investigate the long-term effects of messages and changes in disaster preparedness behaviors. Moreover, we are going to investigate the heterogeneity of the effects due to an occupation. This survey will give us an insight into what kinds of messages are effective for promoting evacuation and how the effects changes according to an occupation.
External Link(s)

Registration Citation

Citation
Kitano, Shodai and Fumio Ohtake. 2022. "Evaluating the Effects of Nudge Messages to Promote Early Evacuation." AEA RCT Registry. July 13. https://doi.org/10.1257/rct.9629
Experimental Details

Interventions

Intervention(s)
Providing three nudge messages and an one control message.
Nudge message1: the message which communicates social norms and potential externality of evacuation with a gain framing
Nudge message2: the message which may change respondents' reference points into a worst situation
Nudge message3: the message which emphasize social norms around respondents
We are going to provide these messages in online questionnaire.
Intervention Start Date
2022-06-22
Intervention End Date
2022-06-24

Primary Outcomes

Primary Outcomes (end points)
the willingness of early evacuation.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
whether respondents stock water and food and other goods
whether they check hazard maps, evacuation routes, and evacuation sites
whether they decide the timing of evacuation.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
In addition to the control message, we will provide three intervention messages which are Message A, Message B and Message C. Message A is the message which communicates social norms and potential externality of evacuation with a gain framing. Message B is the message which may change respondents' reference points into a worst situation. Message C is the message which emphasize social norms around respondents. We will allocates these messages randomly and ask respondents the question about evacuation intentions.
Experimental Design Details
Randomization Method
Randomization done by a computer (done by an internet research company)
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
4,500 individuals in the first survey and 3,000 individual in the follow-up survey
Sample size: planned number of observations
4,500 individuals in the first survey and 3,000 individual in the follow-up survey
Sample size (or number of clusters) by treatment arms
1,125 individuals for each groups in the first survey
750 individuals for each groups in the follow-up survey
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Sample size of each group should be more than or equal to316. <Explanation> According to the prior research (Ohtake et al. 2020), the rates of having intention to evacuate to evacuation sites are 0.232 in control group and 0.357 in one of the treatment group which has exactly a same intervention that we use in this survey. Also, we can get standard deviation from prior research. In addition, we set power = 0.8 and significance level = 0.05 and there are four groups which consist of a one control group and three treatment groups. From these settings, we calculate sample size we need by using R package "TrialSize" and function "OneWayANOVA.PairwiseComparison".
IRB

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number

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