496 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Or condensing, 
First Brother. 
Second 
Brother. 
(a, a) + (a, b). 
(b, b). 
(a, a) + (a, b) 
(b, b) . . 
152ft -45 
28 n 
28 n 
48ft - 19 
Which gives the correlation coefficients as in the following table : — 
Size of 
Family. 
n — 
Correlation Co- 
efficients with 
Assortive Mating. 
r=- 25. 
Correlation as cal- 
culated by Prof. 
Pearson with no 
Assortive Mating. 
4 
1 
•317 
8 
2 
•401 
•333 
16 
3 
•429 
•364 
00 
00 
•476 
•407 
The fraternal correlation is not therefore increased so much by assortive 
mating as the parental-offspring correlation is. The resulting figure is still 
in defect of observation. 
38. The same process may be applied to ascertain the correlation co- 
efficients when three races mix. 
If a standard population is taken and the method just outlined applied 
we get the following correlation table : — 
First Brother. 
Second 
brother. 
(a, a). 
(a, b). 
(b, b). 
(b, c). 
(c, c). 
(c, a). 
(a, a) . 
1 6ft - 9 
8 n 
ft 
2ft 
ft 
8 ft 
(a, b) . 
8 n 
36n -18 
8ft 
9 ft 
2ft 
9 ft 
(b, b) 
n 
8 ft 
16ft -9 
8 ft 
ft 
2ft 
(b } c) . . 
2 n 
9 ft 
8 ft 
36ft - 18 
8ft 
9ft 
(c, c) . 
n 
2 ft 
ft 
8 ft 
16ft -9 
8ft 
( c ) a) . 
8 n 
9ft 
2 ft 
9ft 
8 ft 
36ft - 18 
Then if n = l the contingency coefficient is r = ' 449, and when n = 2, r = - 569, 
much higher values, which will be further increased if assortive mating 
