Statistical Theory of Accident Proneness

Abstract

THE scientific investigation of industrial accidents may be regarded as commencing in 1919 with the publication of a report by Prof. Major Greenwood and H.M. Woods for the Industrial Health Research Board, then known as the Industrial Fatigue Research Board, the data in which indicated that the hypothesis that persons were different in their liability to accidents from the start gave the best fit to the observed distributions. The mathematical considerations underlying these theoretical distributions were examined by Prof. Greenwood and Mr. Udny Yule in a paper published in the Journal of the Royal Statistical Society in 1920. A further paper on theory and observation in the investigation of accident causation by E. G. Chambers and G. Udny Yule has now appeared in the supplement to the same Journal (7, 89-109 ; 1941). In this, Mr. Yule gives a note on the statistical theory of accidents with special reference to the time factor, application of which to accident data leads to the conclusion that a lengthy period of experience is necessary for an individual proneness to accidents to manifest itself fully. Accident proneness may be regarded as a latent disposition needing certain circumstances to reveal it, rather than as an active function which is constantly in operation. Individual differences in accident proneness may, therefore, play their part chiefly in the earlier period of exposure to risk, their importance diminishing as the period of exposure increases. The maximum benefit gained by selective tests for proneness is, therefore, likely to accrue when the tests are applied to new entrants into risky occupations. The chief contributors towards accident rate might thus be found and eliminated during their most vulnerable periods. This conclusion is supported by the observed fact that selective tests are of much less value when applied to experienced workers than they are when given to new entrants.