1888.] 



Co-relations and their Measurement. 

 Table Y. 



143 



analogous to what was observed in kiaship, as I showed in my paper 

 read before this Society on " Hereditary Stature " ('Roy. Soc. Proc.,'vol. 

 40, 1886, p. 42). The statures of kinsmen are co-related variables; ^j 

 thus, the stature of the father is correlated to that of the adult son, I 

 and the stature of the adult son to that of the father ; the stature of 

 the uncle to that of the adult nephew, and the stature of the adult 

 nephew to that of the uncle, and so on ; but the index of co-relation, -4- 

 which is what I there called "regression," is different in the 

 different cases. In dealing with kinships there is usually no need 

 to reduce the measures to units of Q, because the Q values are alike 



in all the kinsmen, being of the same value as that of the popula- 



tion at large. It however happened that the very first case that I 

 analysed was different in this respect. It was the reciprocal relation 

 between the statures of what I called the " mid-parent " and the son. 

 The mid-parent is an ideal progenitor, whose stature is the average of 

 that of the father on the one hand and of that of the mother on the other, 

 after her stature had been transmuted into its male equivalent by the 

 multiplication of the factor of 1*08. The Q of the mid-parental statures 

 was found to be 1*2, that of the population dealt with was 1'7. Again, 

 the mean deviation measured in inches of the statures of the sons was 



