Cll 



Tables for Statisticians and Biometricians 



[XVI 



Illustration. The following table provides data of the health of male year-old 

 babies arranged in two categories only, " Satisfactory " and " Unsatisfactory," in 

 relation to their weight * : 



Health of Year-old Male Baby. 

 Weight in Ibs. (Central Values). 



We have the following constants for this biserial table : 



|(1 - a) = 182/574 = '317,073, 

 hence a = '365,854. 



Interpolating by aid of Table III, Part I, and using the forward difference 

 formula to second differences, we find z = '356,2291. Thus 



- a)l z = '890,0825. 

 Table II of this Part gives by first differences 



|(1 -)/* = '89008. 

 The mean weight and standard deviation of the entire population are given by 



y = 18-834,495 Ibs., <r y = 3'006,365 Ibs., 

 where Sheppard's adjustment has been used. 



* See Earn and Pearson, "Study of the Data provided by a Baby Clinic in a large Manufacturing 

 Town," p. 114, Drapers' Company Research Memoirs, Studies in National Deterioration, No. X, Cam- 

 bridge University Press. 



