Citation

Wood LA, Krider DW, Fezer KD. J. Saf. Res. 1979; 11(4): 172-175.

Copyright

(Copyright © 1979, U.S. National Safety Council, Publisher Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The much-publicized Biorhythm Theory claims that humans have a 23-day physical cycle, a 28-day emotional cycle, and a 33-day intellectual cycle. Transitions between the positive and negative halves of each cycle are held to be dangerous critical days, which can be calculated precisely from the date of birth. If true, the proportion of accidents occurring on the victims' critical days should exceed chance expectations. Records of 700 mostly self-inflicted injuries were randomly selected from hospital emergency room files. Dates of birth and the accident were used to calculate, by computer, the percentage of accidents occurring on the victims' critical days; 27.4% of the accidents occurred on critical days compared to the 26.6% expected by chance. When the definition of critical days was broadened to include the days before and after each critical day defined narrowly, the corresponding percentages were 57.4 and 56.9. When the numbers of observed and expected accidents were calculated for the seven categories of single, double, and triple critical days defined narrowly, and then for critical days defined broadly, the results were again readily attributable to chance.