A re-examination of seasonal variation in suicides in Australia and New Zealand.

BACKGROUND To examine the seasonality of suicides in Australia and New Zealand during the period 1981 to 1993. METHODS A chi-square test and a harmonic analysis were used to detect the seasonality of the suicide data. RESULTS The reduced amplitude and a smaller proportion of variance accounted for by seasonality suggested the seasonal effect on suicide is greatly diminished. The absence of biseasonal distribution of female suicides was also consistently found in the two countries. The finding was contrary to the reported results in seventies in many Western countries. CONCLUSIONS The change in living condition, roles of males and females and communication pattern resulted in the reduction of climatic and environment effect in the seasonality of suicides were suggested. LIMITATIONS The results would be better if a longer series of suicide date were available.