XCV111 



Tables for Statisticians and Biomelricians 



[XV 



Illustration (ii). Considering the data for the Incidence of Enteric Fever on 

 p. xciii above, we had, for the distribution constants, 



Mean = 18-9680 yrs., Mode = 13-3884 yrs., 

 /*2 = 3-821,776*, 0- = 1-954,936*, 



& = 1-033,412, /3 2 = 4-348,825. 



Probable Error of Mean = 1*954,936 x 5 x '67449/V8689 

 = -070728 yrs. 



Proceeding exactly as in the previous illustration we find the ratio of the 

 probable error of the mode to that of the' mean = 2*9825. 



Hence Probable Error of Mode = "070728 x 2'9825 



= -2109 yrs., 

 and our results would be stated as 



Mean = 18-9680 + '0707, 



Mode =13-3884 '2109, 

 both in years. 



Although the "belt" for the mode is three times that for the mean, the 

 accompanying diagram shows that it still gives valuable information as to the 

 likely error in placing the position of maximum incidence. We are unlikely 

 to be in error when we say that the maximum incidence of enteric occurs in the 

 14th year. 



INCIDENCE OF ENTERIC FEVER AT VARIOUS AGES FROM \vi\ - IBQS 



Btll Jiretnie-SRB. = W-968O 1 Z-S>-0107 

 = 18-791 to 19-14$ 



Btlt i Mxfe t Z-SRE. - 13-5884 Z-5X-2HO 

 = 12-861 to 13-916 



McxW OrdiiuJe = 005-5 



\ 



AGE IK YEARS 



* In working units of five years. 



