Citation

Kurucz CN, Khalil TM. J. Saf. Res. 1977; 9(4): 150-158.

Affiliation

Kurucz, Charles N.: U Miami, Coral Gables

Copyright

(Copyright © 1977, U.S. National Safety Council, Publisher Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Recently, there has been a growing interest in a theory of biological cycles called biorhythm. The theory purports that there are three cycles in human beings: a 23-day physical cycle, a 28-day emotional cycle, and a 33-day intellectual cycle. The cycles are fundamental to life, exactingly regular, and continue to fluctuate involuntarily from positive states in the first half of the cycle to negative states in the second half. The days on which transition from one state to the other are termed critical days, it has been reported that safety and performance may suffer as these days and the cycles. Several applications of this theory in the areas of accident prevention and human performance have been suggested by other researchers. This paper examines the biorhythm theory from a theoretical probability point of view and provides a method for determining critical days and comparing expected and actual results when the biorhythm theory applied. The implications for analysis of several different definitions of critical days are noted, especially with regard to changes in the probabilities used for calculations. Use of the method and analyzing actual accident data failed to support current biorhythm theory.