Explanatory Note to Tables XI. to XX. 



These Tables deal with the characters exhibited by the inmates at each 

 individual asylum. The mean, standard deviation and coefficient of variation, with 

 their probable errors, of each character have been determined. These terms are 

 perfectly familiar ones to scientific men handling similar data, but perhaps it may 

 be useful to add a word of explanation as to their meaning for those to whom the 

 method of dealing with the results of such measurements is a novelty. The mean 

 is, of course, the average size for each character. The standard deviation is a 

 measure of the degree of spread or scatter of the various sizes round the mean. 

 If the various sizes differed very little from the average size, the standard devia- 

 tion would be small and would indicate a low degree of variability, while if the 

 sizes were of all sorts — very large and very small — and therefore differed a good 

 deal from the average, the standard deviation would be much greater, and, as 

 already stated, would give an estimate of the degree of scatter round the mean. 

 The coefficient of variation is the ratio of the standard deviation to the mean, con- 

 sidered as a percentage. 



Tables XI. and XII. deal with the Head Length ; Tables XIII. and XIV. 

 Head Breadth ; Tables XV. and XVI. Head Height; Tables XVII. and XVIII. 

 Cephalic Index ; and Tables XIX. and XX. Stature. The values given in the 

 Tables are those found by calculation on the basis of a 5 mm. grouping. In 

 the case of stature, a 3 inch unit was adopted. The addition of the probable error 

 furnishes the means of ascertaining (i) how far the values may differ in future 

 samples, and (2) what significance is to be attached to the differences existing 

 in each character among the various asylums. As explained in the introduction 

 to the Report no discussion as to the significance of the differences found or of 

 the results generally is to be entered into here. The Tables merely give the facts 

 relating to the measurements in a condensed form. 



In performing the analyses of the data from individual asylums, account was 

 taken of exceptional cases — those whose characters were undoubtedly affected by 

 pathological and other conditions. There may be others whose characters are 

 similarly affected in a lesser degree, but a special research would be required to solve 

 this. Those omitted in the determination of the constants for individual asylums are 

 undoubtedly exceptional. Of the 4436 males observed, 55 were excluded, and of 

 the 3951 females, 26 were thus excluded, leaving 4381 males and 3925 females to 

 be subjected to enquiry. 



