iv.] SCHEMES OF DISTRIBUTION AXD OF FREQUENCY. 49 



by the process of comparison. Suppose the second 

 Scheme to refer to the successes of students from another 

 hospital, we should draw the two Schemes in opposed 

 directions, just as was done in the Strength of Pull of 

 Males and Females, Fig. 5, and determine the Grade 

 in either of the Schemes at which success was equal. 



Schemes of Frequency. The method of arranging 

 observations in an orderly manner that is generally 

 employed by statisticians, is shown in Fig. 3, page 38, 

 which expresses the same facts as Fig. 2 under a different 

 aspect, and so gives rise to the well-known Curve of 

 "Frequency of Error," though in Fig. 3 the curve is 

 turned at right angles to the position in which it is 

 usually drawn. It is so placed in order to show more 

 clearly its relation to the Curve of Distribution. The 

 Curve of Frequency is far less convenient than that of 

 Distribution, for the purposes just described and for 

 most of those to be hereafter spoken of. But the Curve 

 of Frequency has other uses, of which advantage will 

 be taken later on, and to which it is unnecessary now 

 to refer. 



A Scheme as explained thus far, is nothing more than 

 a compendium of a mass of observations which, on being 

 marshalled in an orderly manner, fall into a diagram 

 whose contour is so regular, simple, and bold, as to 

 admit of being described by a few numerals (Table 2), 

 from which it can at any time be drawn afresh. The 

 regular distribution of the several faculties among a 

 large population is little disturbed by the fact that its 



