Development and validation of the Japanese version of the psychological preparedness for disaster threat scale

Abstract Background Japan is highly vulnerable to hydro-meteorological hazards such as typhoons, severe storms, and flooding, which cause recurring damage to life and property. Consequently, there is a need for a culturally adapted tool to assess individuals’ psychological readiness for these hazards in Japan. Existing Japanese instruments tend to emphasize the behavioral and material aspects of disaster preparedness while overlooking psychological preparedness. This study developed and validated a Japanese version of the Psychological Preparedness for Disaster Threat Scale (PPDTS-J23), focusing on preparedness for hydro-meteorological hazards. Methods A nationwide online survey was conducted ( N = 773), followed by a one-month follow-up survey of a subsample for test-retest analysis ( n = 191). The factor structure was examined by exploratory and confirmatory factor analyses and cross-validated in two randomly assigned subsamples. Measurement invariance across sex and age groups, internal consistency, test-retest reliability, and convergent and discriminant validity were also assessed. Results Exploratory and confirmatory factor analyses supported a three-factor structure: knowledge and management of the external situational environment, management of one’s emotional and psychological response, and management of one’s social environment. Confirmatory factor analysis indicated adequate model fit (comparative fit index = 0.942, root mean square error of approximation = 0.062). The final 23-item version demonstrated high internal consistency for the total scale (α = 0.956) and its subscales (α = 0.919, 0.936, and 0.827), and measurement invariance was supported across sex and age groups. Test-retest reliability was acceptable for the total score (intraclass correlation coefficient = 0.780), although the coefficient for the management of one’s social environment subscale fell below the adopted criterion (0.657). Convergent validity was supported, whereas discriminant validity was only partially supported. Conclusions The PPDTS-J23 is a reliable measure of psychological preparedness for hydro-meteorological hazards in the Japanese context. The scale can be used in disaster education programs to evaluate program outcomes and to characterize the preparedness profile of a group, inform community-based disaster risk reduction, and support mental health planning amid increasing climate-related disaster risks.