vii.] DISCUSSION OF THE DATA OF STATURE. 103 



relation between the major and minor axis of the 

 ellipses was changed 3 per cent. ; and their inclination 

 to one another was changed less than 2V 



It is obvious from this close accord of calculation 

 with observation, that the law of Error holds through- 

 out with sufficient precision to be of real service, and 

 that the various results of my statistics are not 

 casual and disconnected determinations, but strictly 

 interdependent. 



I trust it will have become clear even to the most 

 non-mathematical reader, that the law of Regression 

 in Stature refers primarily to Deviations, that is, to 

 measurements made from the level of "mediocrity to the 



1 The following is a more detailed comparison between the calculated 

 and the observed results. The latter are enclosed in brackets. The letters 

 refer to Fig. 11 : — 

 Given — 



The "Probable Error" of each system of Mid- Parentages = 1*22 

 inch. (This was an earlier determination of its value ; as already said, 

 the second decimal is to be considered only as approximate.) 

 Eatio of mean filial regression = f. 

 " Prob. Error" of each Co-Fraternity = U50 inch. 



Sections of surface of frequency parallel to XY are true ellipses. 



(Obs. — Apparently true ellipses.) 

 MX : YO = 6 : 17*5, or nearly 1 : 3. 



(Obs .— 1 : 3.) 

 Major axes to minor axes = *J 7 : ^/2 = 10: 5*35. 



(Obs.— 10 : 5-1.) 

 Inclination of major axes to OX = 26° 36'. 



(Obs. 25°.) 

 Section of surface parallel to XZ is a true Curve of Frequency. 



(Obs. — Apparently so.) 

 "Prob. Error", the Q of that curve, = 1.07 inch. 



(Obs.— 1-00, or a little more.) 



