Statistical Analysis of the birth charts of serial killers
by Jan Ruis
Correlation, Vol. 25(2) 2007/2008, pp7-44
In this study, hypotheses of astrologers about the predominance of specific astrological factors in the birth charts of serial killers are tested. In particular, Mutable signs (Gemini, Virgo, Sagittarius and Pisces), the 12th principles (12th house, Pisces, Neptune) and specific Moon aspects are expected to be frequent among serial killers as compared to the normal population.
A sample consisting of two datasets of male serial killers was analysed: one set consisting of birth data with a reliable birth time (N=77) and another set with missing birth times (12:00 AM was used, N=216). The set with known birth times was selected from AstroDatabank and an astrological publication. The set with unknown birth times was selected from three specialised sources on the Internet. Various control groups were obtained by shuffle methods, by time-shifting and by sampling birth data of 6,000 persons from AstroDatabank. Theoretically expected frequencies of astrological factors were derived from the control samples. Probability-density functions were obtained by bootstrap methods and were used to estimate significance levels. It is found that serial killers are frequently born when celestial factors are in Mutable signs (with birth time: p=0.005, effect size=0.31; without birth time: p=0.002, effect size=0.25). The frequency of planets in the 12th house is significantly high (p=0.005, effect size=0.31, for birth times only) and the frequency distribution of Moon aspects deviates from the theoretical distribution in the whole sample (p=0.0005) and in the dataset with known birth time (p=0.001). It is concluded that, based on the two datasets, some of the claims of astrologers cannot be rejected.