Suicide, one of the most serious social problems in modern Japan, is known to be caused by many complex factors. Regional correlation study on local suicide rates and various affecting factors attracts much attention from the viewpoint of regional countermeasure for decreasing suicide rates. In this study, a statistical approach to get information on reasons of suicide in Japan has been carried out by searching key factors affecting suicide rates. A support regression method as a nonlinear regression procedure was applied to male and female suicide rates of 47 prefectures as dependent variables and 54 kinds of various regional factors as explanatory variables. Twelve determinants for each men and women, respectively, were obtained which reproduce the suicide rates of prefectures with a statistical significance level. Among those determinants, psychiatric social worker, household income, and patient rate for men, and consultation situation of trouble and stress, birthrate, and overtime for women dominantly affect suicide rates. New determinants not verified in previous studies, such as psychiatric social worker, overtime, and mental status contribute, while unemployment rate and divorce rate so far frequently verified do not contribute. A countermeasure for decreasing the suicide rate in Akita prefecture with the highest suicide rate in Japan, was proposed on the basis of values of determinants.
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