‘The fact that many applications of probability are based on belief or faith should not discourage us; for it is better to do something, though it may not be quite reliable, than nothing.’
J. V. Uspensky
This paper is concerned with the application of probability theory to sickness. An attempt is made to explore the form, and in particular the standard deviation, of the distribution of the sickness experienced by a body of lives. It appears that, in the past, none but empirical investigations have been made in this field, the theoretical foundation being entirely lacking. The only exceptions are Sir George Hardy's paper in J.I.A. Vol. XXVII, and the paper in J.S.S. Vol. VII by R. E. Beard on The standard deviation of the distribution of sickness. This statistic, as Beard points out, appears to have been practically ignored by British actuaries hitherto.