OF LOGICAL CLASS-FEEQUENCIPIS, ETC. 
131. 
Only in the case of hgs. 17 and 21 does the general appearance of the surface 
resemble that shown in fig. 4 ; in all the other cases the greater part of the surface is 
given by the conditions of inferior congruence. Mere inspection of the figures shows 
that while, e.g., a very slight alteration of the actual values of (BC) and (AC) would 
lead to a lower limit for (AB) (c/i figs. 16 and 20) the associations between A and E 
and A and C would have to be very largely increased indeed before we could infer 
(BC) >0. A study of such figures as these would, I think, lead to a good deal 
more caution in statistical inference. 
§ 37. It may be remarked that while the conditions of inferior congruence for 
second-order groups always give the limits dr 1 to the corresponding associations, 
s 2 
