Development of the Japanese version of the three-item loneliness scale

BACKGROUND: Loneliness is a major risk factor for mental and physical health worldwide. The Three-Item Loneliness Scale (TIL Scale; Hughes et al., 2004) has been widely applied to measure loneliness in a simplified format, but no validated Japanese version has been developed. This study adapted the TIL Scale into Japanese and tested its reliability and validity. METHODS: The original English version of the TIL Scale was translated into Japanese, and the expressions of the Japanese version were confirmed by a back translation procedure. The translated scale was then administered to Japanese respondents recruited from an online research panel (N = 1020) and an online crowdsourcing service (N = 500). To analyze the data containing polytomous responses to the items in the scale, this study used categorical Confirmatory Factor Analysis and the Generalized Partial Credit Model based on the Item Response Theory. To evaluate the psychometric properties of the scale, this study examined factorial validity, reliability, information curves, and the associations of the scale score with demographic variables (age, gender, marital status, and living arrangements), the scores of the Revised UCLA Loneliness Scale (R-UCLA), the Big Five scale of personality traits, and the sizes of personal networks. RESULTS: The translated TIL Scale showed essential unidimensionality and characteristics to differentiate among respondents at different levels of loneliness. The scale score was related positively with the scores of R-UCLA and neuroticism and negatively with the scores of extraversion, conscientiousness, openness, agreeableness, and the sizes of overall and support networks. Those who were unmarried and alone recorded a higher score on the scale than those who were married and living with someone. Age showed a negative correlation with the scale score only in Sample 1, in which the equal allocation procedure was introduced for the age stratum. CONCLUSIONS: The results indicate that the Japanese version of the TIL Scale demonstrates adequate reliability and validity for the assessment of loneliness. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s40359-019-0285-0) contains supplementary material, which is available to authorized users.