16 Messrs. L. Hill and M. Greenwood, Jun. [Oct. 1, 
the latter’s probable error, but this does not prove linearity of regression,* 
nor can we apply Blakeman’s test for linearity (8), since the scale of caisson 
illness is not quantitative. | 
Finally, the mean square contingency was determined by means of the 
grouping shown in Table V, and proved to be 0°544 + 0:078.+ : 
While, therefore, the exact value of the relationship between body weight 
and decompression effects is hardly expressible in terms of normal correla- 
tion, it can scarcely be less close than that implied by a contingency 
coefficient of at least 0°3; in other words, the two variables are quite 
definitely correlated. We have at present no means of extending this 
analysis to any other group of animals. 
Table V. 
Weight in grammes. 
Survived. | 
=) 
= 
@ 
Qu 
Kj 
io) 
—s 
= 
mn 
40— 60 | 
60— 80 | 
80-—100 
ee 
DH WH DIAN MAOAE 
SSSSSSASAUASA 
100—120 
120—140 
140—160 . 
160—180 | 
180—200 
200—220 
220—240 
300—320 
340—360 
COCHKHHNPHNONaA 
SSSSSSSSSASH 
DWH AOHARHANARO 
SSSdSSONSUSSS 
oy 
or 
S 
Totalsy.c-cderscrs 34 °0 
ive) 
pat 
ral 
Observations falling at a class limit (e.g., 60) were reckoned as 0°5 in each class. 
(b) Rabbits. 
Our experiments have not been numerous, but the following are 
suggestive :-— 
Exp. 5.11.06.—Three rabbits, one full grown, another of [medium size, a 
* In any case, but little weight can be attached to the value obtained for 7, since there 
are only two arrays available. It seemed best, however, to record the value for 
comparison. 
+ Deduced by multiplying the probable error obtained from the ordinary formula 
by 4/3. The complete formula of Blakeman and Pearson (9) gave a lower value, perhaps 
owing to an undetected slip in the rather involved arithmetical computation. The exact 
significance of the coefficient may be realised by comparing its value with those obtained 
by Pearson (7) for the contingency between undoubtedly related variables :— 
Stature in father and son ... eee oh . C,=0513 
Hair colour in brothers ae, Na se .. COC, =0°614 
Occupation in fathers and sons _... ies ». CO, = 06275 
See pp. 21, 22 (7). 
