370 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
where d represents the actual deviation and = the sum, 2 the number 
of individuals; o the standard deviation. 
“Correlation tables” show graphically whether or not there is 
correlation. If, as in Figure 64, we want to find out what is the rela- 
tionship between total yield of oats and number of culms to the plant, 
we may make a table with subject classes arranged perpendicularly, 
and the relative classes, horizontally. If the individuals tend to group 
themselves about a diagonal ranging from upper left- to lower right- 
hand corners, the amount of correlation is quite marked. Complete 
correlation would be represented by a single line of points along this 
diagonal. No correlation would be shown by random distributing 
2 3 4 5 6 7 
0-1; 3 3 
1-2] 28 19 3 50 
2-3] 18 66 20 1 1 {106 
34] 1 42 58 7 1 109 
4-5 7 59 3 80 
5-6 2 «14 2 42 
6-7 4 3 7 
7-8 1 1 2 
8-9 1 1 
50 134 167 38 10 1 400 
Fic. 64.—Correlation table of 4oo plants of Sixty-Day oats. Total yield of 
plant in grams, subject. Number of culms per plant, relative. 1910. Coefficient 
of correlation=0.7120.017. (From Love and Leighty, 1914.) 
over the whole rectangle. Inverse correlation would tend to give a 
grouping about a diagonal ranging from the upper right- to lower 
left-hand corners. 
In the particular correlation table used for illustration, the coeffi- 
cient of correlation (7,y) turns out to be 0.7120.017. Since com- 
plete correlation would be 1, the degree of positive correlation is very 
high, as we might expect. The correlation table was used quite 
effectively by Galton, as we shall now show. 
STATISTICAL STUDY OF INHERITANCE! 
EDWIN GRANT CONKLIN 
Francis Galton was one of the first who attempted to reduce the 
mass of conflicting observations on heredity and variation to some 
tFrom E. G. Conklin, Heredity and Environment (copyright 1920). Used by 
special permission of the publishers, The Princeton University Press. 
