94 The Correlation Coefficient of a Polychoric Table 
be divided as in the diagram by planes drawn parallel to the yz plane at the points 
X = III, X = h,^ ... and by planes parallel to the xz plane at the points y = k-^, 
y -~= k.2 .... Let the planes intersect in lines whose projections are the points (/i^, Jcj), 
{h^, A'a), etc., contracted to 11, 12, etc., where the first figure is the suffix of h and 
the second figure is the suffix of k. 
h 
ho 
"■7-1 
h 
P-1 
nil 
11 
"21 
21 
^31 
31 
41 
'^•1 j-m.i 1 
> \ 
'«12 
12 
22 
'''32 
32 
42 
n.2 1 
) 
^13 
J3 
^^23 
23 
«33 
33 
43 
w.3 
14 
24 
n. 
«2. 
N. . . 
The frequencies in the cells and the marginal totals are indicated bv >iii, Wi2, 
etc., and %., n^. ... n.^, n..^, etc., as shown in the diagram. 
The surface may also be regarded as divided at each point 11, 12, into four 
quadrants. One of these quadrants is shown by the dotted lines in the diagram. 
The quadrant in the position shown, viz. the left upper or ( — ) quadrant will be 
