Faculty of Medicine, Center for Environmental and Respiratory Health Research, University of Oulu, Oulu, Finland.
BMJ Open. 2019 Jan 15;9(1):e022759. doi: 10.1136/bmjopen-2018-022759.
To test whether homicides in Finland vary according to moon phases.
A time series study.
Finland.
6808 homicides committed in 1961-2014.
Daily numbers of homicides.
The daily numbers of homicides were related to eight moon phases and the illuminated percentage of the moon disc using negative binomial regression. To identify lunar patterns, piecewise linear terms of lunar days were used, together with changes from one moon phase to another. Homicides were similarly regressed on quintiles of the illuminated percentage of the moon disc. A periodic term of length 29.53 days was included to detect cyclic patterns. The results were adjusted for sex, age, secular trend, distance from the moon, seasons, weekday, major holidays and temperature.
During the full moon, 15% less homicides were committed than during the new moon (RR 0.85; 95% CI 0.77 to 0.94) and 86% less during the lightest quintile of illumination compared with the darkest quintile (RR 0.14; 95% CI 0.04 to 0.50). Adjustments did not change the results. Piecewise linear regressions showed a significant decline in homicides at the full moon and a rise thereafter. The full moon drop in homicides was directionally similar for seasons, weekdays, sex, age and time periods, and it was particularly pronounced in the early part of period studied (1961-1974). Periodic regression showed a regular cyclic pattern of length 29.53 days (p~0.035).
Contrary to current scientific opinion, an association exists between moon phases and homicides, and contrary to what has been previously assumed, homicides declined during the full moon, especially in earlier decades. However, the causality of the association remains elusive.
检验芬兰的杀人案是否与月相有关。
时间序列研究。
芬兰。
1961-2014 年间发生的 6808 起杀人案。
杀人案的日发生数。
采用负二项回归，将每日杀人案数量与 8 个月相和月盘的照明百分比相关联。为了识别月相模式，使用了月相日的分段线性项，以及从一个月相到另一个月相的变化。杀人案也被回归到月盘照明百分比的五分位数上。包含一个 29.53 天长度的周期性项，以检测循环模式。结果根据性别、年龄、长期趋势、与月亮的距离、季节、星期几、主要节日和温度进行了调整。
满月时，杀人案比新月时减少了 15%（RR 0.85；95%CI 0.77 至 0.94），与最暗五分位数相比，最亮五分位数的照明减少了 86%（RR 0.14；95%CI 0.04 至 0.50）。调整后结果不变。分段线性回归显示，在满月时杀人案显著下降，之后上升。满月时杀人案的下降在季节、星期几、性别、年龄和时间段上方向相似，在研究期间的早期（1961-1974 年）尤其明显。周期性回归显示出一个长度为 29.53 天的规则循环模式（p~0.035）。
与当前的科学观点相反，月相与杀人案之间存在关联，与之前的假设相反，杀人案在满月时下降，尤其是在早期几十年。然而，这种关联的因果关系仍难以捉摸。
