292 On Theories of Association 
Now here are a few of Mr Yule's percentage coefficients : 
(1) Imbeciles and Deaf-mutes (Yule, loc. cit. pp. 33 — 34). 
Imbecile 
Non-Imbecile 
Totals 
Deaf- Mute 
Non-Deaf-Mute ... 
451 
48,431 
14,795 
32,464,323 
15,246 
32,512,754 
Totals 
48,882 
32,479,118 
32,528,000 
g„=0-877 
? ft = 2-809 
(2) Datura (Yule, loc. cit. p. 37). 
Violet 
White 
Totals 
Prickly . . . 
Smooth ... 
47 
12 
21 
3 
68 
15 
Totals ... 
59 
24 
83 
q v = - 7-840 
q h = -10-882 
(3) Houses in course of erection in Urban and Rural Districts (Yule, loc. cit. 
p. 62). 
Built 
Building 
Totals 
Urban ... 
4960 
50 
5010 
Rural 
1749 
12 
1761 
Totals 
6709 
62 
6771 
^ = 6-714 
<7 ft =0-317 
(4) Eye-colour in Father and Son (Yule, loc. cit. p. 34). 
Father. 
o 
02 
Light 
Not-Light 
Totals 
Light 
471 
148 
619 
Not-Light ... 
151 
230 
381 
Totals 
622 
378 
1000 
y„ = 36-570 
y A = 36-457 
(5) Developmental Defects and Dullness (Yule, loc. cit. p. 45, where the 
numbers are reduced to 10,000). 
With Defects 
Without 
Totals 
Dull 
888 
1186 
2074 
Not-Dull ... 
1420 
22793 
24213 
Totals 
2308 
23979 
26287 
^ = 33-528 
q h = 36-951 
