STUDIES IN STATISTICAL REPRESENTATION. 495 
In this case we must have given seven values of y. 
Writing 7, ¥» y, and y for the minors of &, €, € and 1 in this 
determinant, the equation becomes 
EF ys — Fy. + &y, - yy = 0 sec ceerccccce (59) 
15. Graphs of curves.—The graphs of some of the curves 
SB Nii ea Ee os ST SY at ea eee a Fig. 3. 
A, v2"; Boa® +a; C, (a® + atl ae eee es Fig. 4. 
eee ob, 2! cal; Ci(ba' + a1); D(a +cat!) 1... Big.d. 
These give a sufficient indication of curves with two 
indices only, and are sufficient to indicate the utility of 
such formule as have been considered. It is obvious that 
VisiCalc < 
Sa SesieiNts 
SRK 
sie 
ae 
| 
LJ 
is 
(a a ig 
a. aaamm 
[eas aa a 
3 4 0 | 2 3 4 
Fig. 3. 
