Measuring and Addressing Radiation Stigma: Beliefs, Attitudes, and Choices in Survey Experiments

Last registered on October 07, 2026
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Pre-Trial

Trial Information

General Information

Title
Measuring and Addressing Radiation Stigma: Beliefs, Attitudes, and Choices in Survey Experiments
RCT ID
AEARCTR-0019851
Initial registration date
October 01, 2026

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
October 07, 2026, 10:33 AM EDT

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

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Primary Investigator

Name
Hidetoki Nakayama
Affiliation
Graduate School of Economics, Osaka university
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Other Primary Investigator(s)

PI Name
Fumio Ohtake
PI Affiliation
Center for Infectious Disease Education and Research and Graduate School of Economics, The University of Osaka
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Additional Trial Information

Status
In development
Start date
2026-10-02
End date
2026-11-06
Keywords
Behavior, Environment & Energy, Lab
Additional Keywords
Radiation stigma, Beliefs, Social norms, Information provision, Survey experiments
JEL code(s)
C93, D83, D91
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This study examines the measurement of and responses to radiation stigma arising from a nuclear power plant accident. It examines perceived health risks, beliefs about others’ attitudes, and how information affects attitudes and choices concerning people and products associated with an affected region. Such stigma may manifest in diverse and subtle forms, while the sensitivity of expressing avoidance complicates its measurement. Using the Fukushima Daiichi nuclear accident as the empirical setting, the project combines multiple measurement approaches with randomized information interventions.

The project comprises three surveys with independent samples. A preliminary survey combines direct questions, indirect elicitation methods, and predictions of others’ reported and privately held attitudes to assess reluctance and misperceptions. Its findings will also inform the construction of an information treatment.

Study 1 examines how information about scientific assessments, others’ risk perceptions and attitudes, and the social consequences of behavior affects respondents’ own reluctance, health-risk beliefs, and predictions of others’ attitudes. Study 2 examines whether information affects product choices with real consequences: respondents select a product, and lottery winners receive their chosen product. Complementary conjoint tasks examine choices involving products and social interactions. Together, the studies assess how information affects beliefs, expressed attitudes, and choices across different contexts.
External Link(s)

Registration Citation

Citation
Nakayama, Hidetoki and Fumio Ohtake. 2026. "Measuring and Addressing Radiation Stigma: Beliefs, Attitudes, and Choices in Survey Experiments." AEA RCT Registry. October 07. https://doi.org/10.1257/rct.19851-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
Studies 1 and 2 compare information interventions concerning radiation stigma following the Fukushima Daiichi nuclear accident with control conditions. The interventions provide information about scientific assessments, others’ beliefs and attitudes, or the social consequences of behavior. One information condition is informed by the preliminary survey.
Intervention Start Date
2026-10-23
Intervention End Date
2026-10-31

Primary Outcomes

Primary Outcomes (end points)
Preliminary survey: the gap between predictions of others’ privately held reluctance and indirectly estimated reluctance, and the difference between predictions of others’ privately held attitudes and survey answers (the T–R gap).

Study 1: respondents’ own reported reluctance, predictions of others’ reluctance, and the T–R gap in the no-information condition.

Study 2: selection of a Fukushima product in a product-choice task with real consequences.
Primary Outcomes (explanation)
The preliminary survey uses direct questions and indirect elicitation methods to measure reluctance toward people and products associated with Fukushima. Predictions of others’ survey answers (Reported, R) are distinguished from predictions of their privately held attitudes (Truthful, T).

Study 1 measures respondents’ own reluctance and predictions of others’ reluctance, with the latter elicited separately in the R and T frames. The difference between mean T- and R-frame predictions is a primary outcome in both the preliminary survey and Study 1’s no-information condition (A0), evaluated separately in each survey.

In Study 2, respondents select a product, and lottery winners receive their selected product. The outcome records the choice regardless of the lottery result.

Detailed measurement and estimation procedures are specified in the pre-analysis plan.

Secondary Outcomes

Secondary Outcomes (end points)
Study 1: radiation-related health-risk beliefs and treatment effects on the difference between predictions of others’ privately held attitudes and survey answers (the T–R gap).

Study 2: choices and ratings in conjoint tasks, and hypothetical product choices in a multiple price list.
Secondary Outcomes (explanation)
Study 1 distinguishes beliefs about later-life and intergenerational radiation-related health risks. Comparing the T–R gap across information conditions measures treatment effects on the perceived difference between others’ privately held attitudes and their survey answers.

Study 2 includes complementary conjoint tasks measuring choices and ratings, and a multiple price list eliciting hypothetical product choices.

Detailed task designs are described in the pre-analysis plan. Analysis specifications for Studies 1 and 2 will be finalized in the pre-analysis plan update before each study begins.

Experimental Design

Experimental Design
The project comprises three online surveys administered by a survey company to independent, non-overlapping samples of panel members in Japan aged 20–69. Target samples are 2,000 for the preliminary survey, 7,200 for Study 1, and 9,600 for Study 2. Additional eligibility criteria are specified in the pre-analysis plan.

The preliminary survey combines direct and indirect measures of reluctance with predictions of others’ attitudes. Its findings inform one subsequent information intervention.

Studies 1 and 2 are planned to begin approximately three weeks after the start of the preliminary survey. The exact timing may change depending on survey preparation and fieldwork progress.

Studies 1 and 2 randomly assign respondents to information or control conditions. Study 1 examines effects on respondents’ own reluctance, health-risk beliefs, and predictions of others’ attitudes. Study 2 examines product choices with real consequences: respondents choose a product, and 100 lottery winners receive their selected product. Complementary conjoint tasks measure choices and ratings.

The designs and analysis plans for Studies 1 and 2 are provisional. An updated registration and pre-analysis plan will be provided before each study begins, documenting any changes and their reasons.
Experimental Design Details
Not available
Randomization Method
Random assignment is implemented by the survey company.

The preliminary survey independently randomizes measurement conditions and the Reported/Truthful belief frame in equal proportions. Studies 1 and 2 assign information conditions in equal proportions. Study 1 additionally randomizes the belief frame within each information condition. Study 2 also includes randomization of task versions and presentation order.

Further randomization details are specified in the pre-analysis plan.
Randomization Unit
Individual respondent.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
18,800 individual respondents: preliminary survey 2,000; Study 1 7,200; Study 2 9,600.
Sample size: planned number of observations
18,800 respondents in three non-overlapping samples: preliminary survey 2,000; Study 1 7,200; Study 2 9,600.
Sample size (or number of clusters) by treatment arms
Preliminary survey: 2,000 respondents, with approximately 1,000 per level of each of three independently randomized binary factors.

Study 1: 1,200 respondents per information condition across six conditions, with 600 per Reported/Truthful belief frame within each condition. If the preliminary-survey-based condition is omitted, allocation is 1,440 per condition across five conditions, with 720 per belief frame.

Study 2: 1,600 respondents per information condition across six conditions, or 1,920 per condition across five conditions if the preliminary-survey-based condition is omitted.

Total sample targets remain unchanged. The inclusion rule for the preliminary-survey-based condition is specified in the pre-analysis plan.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Benchmarks use two-sided tests at the 5% significance level and 80% power. Preliminary survey: approximately 4.1–5.8 percentage points for the gap between predictions of others’ privately held reluctance and crosswise-estimated reluctance, under the illustrative assumptions specified in the pre-analysis plan. Study 1: approximately 0.114 standard deviations for respondents’ own reluctance and 0.162 standard deviations for predictions of others’ reluctance within each Reported/Truthful belief frame. Study 2: with 1,600 respondents per condition, approximately 3.8–4.1 percentage points at an illustrative control selection rate of 20%, and 4.9 percentage points at 50%. Calculation assumptions and supplementary benchmarks are specified in the pre-analysis plan.
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Graduate School of Economics, The University of Osaka IRB
IRB Approval Date
2026-09-09
IRB Approval Number
R80909
Analysis Plan

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