Seasonal Variation in Irish Suicidal Deaths

Lester (2) and Sanborn and S a n b r n ( 5 ) have shown that the suicidal deaths' rates for two different geographical locations in the United States display some evidence of Spring and Fall peaks. This study was an attempt to discover whether there are comparable patterns in the Republic of Ireland. That the statistical returns underestimate the 'true' suicide rate in Ireland seems fairly well established (3, 4) . However, Bruga and Walsh (1) concluded that, although the official statistics do underestimate the 'true' suicide rate, they are likely to reflect valid variations in rate. Computerized records containing sufficiently detailed data for analysis were recorded for the first time from 1971 and are presently available only up until 1975. There were 542 deaths by suicide during this period, and the monthly rates for males and females over the 5 yr. were analyzed by means of a 2 X 12 factorial analysis of variance (Model 11) using sex and month as factors (6, p. 445). The main effect of sex was, as expected, significant ( K . M = 86.74, p .25); iMs and SDs = 6.8, 1.64; 6.6, 4.16; 8.8, 4.21; 10.0, 3.39; 8.8, 2.95; 8.6, 2.97; 9.0, 5.87; 12.0, 2.92; 10.2, 0.84; 7.6, 5.46; 8.2, 1.79; 11.8, 5.07 for January to December, respectively. The interaction of sex and month was non-significant, i.e., there was no significant sex difference in the distribution of suicidal deaths throughout the year. While it is possible that a larger sample, when it becomes available, may indicate seasonal variation in the suicide rate, the present data display no such pattern. This remains the case even when the analysis is performed in terms of seasons, i.e., groups of 3 mo., and when the progressive increase in suicide rate over the 5-yr. period is taken into account.