STATISTICAL INQUIEY 1005 



The percentage of admission and mortality for the year 

 is not obtained by adding the monthly percentages together 

 and dividing by 12, but by ascertaining the average 

 strength, and by rule of three calculating what percentage 

 the total admissions and deaths bear to this. In the 

 example given, the average strength for the twelve months 

 was 594-25, and the total admissions 186 ; therefore 

 186 X 100-=-594-25 = 31"29 per cent, admissions per annum, 

 and 20x100^594-25 = 3-36 per cent, deaths per annum. 



In expressing statistical results, some constant means of 

 comparison must be adopted, such as per cent., per 1,000, 

 or per 10,000, etc. The most common standard used is 

 per cent. 



To ascertain the percentage is a rule-of-three sum. 

 Suppose, for instance, that in a strength of 3,978 horses 

 428 cases of strangles occurred causing 12 deaths, we can 

 ascertain : 



(1) What proportion of the horses were attacked. 



(2) Of those attacked, what was the mortality. 



(3) Of those attacked, what were the recoveries. 



(4) The mortality on the total strength. 



One or two examples of the working will suffice for the 

 others. 



In 428 cases of strangles there are 1-2 deaths. What is 

 the mortality per cent, of those attacked ? 

 12 X 100 



428 



=2-803 per cent. 



In 428 cases of the disease there are 12 deaths. What 

 proportion per cent, recovered ? 



416x100^97.196 per cent. 

 428 



The value of statistical inquiry in questions relating to 

 health, disease, mortality, casting, etc., is obvious. We 

 should know the proportion of horses which are constantly 

 sick, the average length of time under treatment, and the 

 general inefficiency which this represents. 



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