MISCELLANEA. 
I. A Simplified Method of Calculating Frequencies of Occurrence, 
from a Large Number of Unequal Probabilities. 
By Captain A. G. M°KENDRICK, I.M.S., Assistant Director, Pasteur 
Institute of Southern India, Coonoor. 
In the study of epidemics in particular it is desirable to determine, in certain cases, whether 
the proneness of a particular community to recurring attack by disease, is regulated by the laws 
of chance ; or whether other factors are operative. 
Such an investigation must be carried out in two steps ; firstly, from the data given, the 
chance distribution must be calculated, and secondly, the chance distribution must be compared 
with actual figures. 
Problems of this sort occur in many forms, for example : 
(1) If a series of epidemics of varying magnitude occurs in a group of communities, do the 
numbers of communities actually attacked never, once, twice, etc., agree with the numbers 
as calculated by the calculus of Probabilities ? 
(2) If a regiment is attacked by a number of different diseases in a given time, do the 
numbers of men actually attacked by none, one, two, etc. of these diseases, agree with the 
probable numbers 1 
It is only with the first step of the investigation, i.e., the calculation of the probable numbers, 
that this paper will deal. 
M. Greenwood, Jr. {Journal of Hygiene, Vol. x. No. 3, p. 416) in an admirable analysis of 
the statistics of Plague epidemics in the Punjaub, had, amongst others, the following problem to 
deal with : 
In the Amritsar District out of 1,062 villages, 
62 were attacked by plague in 1901 — 2 
506 
445 
669 
276 
604 
1902— 3 
1903— 4 
1904— 5 
1905— 6 
1906— 7 
