242 LIGHT SCIENCE FOR LEISURE HOURS. 



nor is anyone likely to ascribe the longevity of our 

 nobility to the possession of a title. Yet there is 

 nothing in any one of the above inferences which is in 

 reality more unsound than Dr. Stark's inference from 

 the mortality bills, when the latter are considered 

 with due reference to the principles of interpretation 

 which statisticians are bound to follow. 



The fact is, that in dealing with statistics the utmost 

 care is required in order that our inferences may not be 

 pushed beyond the evidence afforded by our facts. In 

 the present instance, we have simply to deal with the 

 fact that the death-rate of unmarried men is higher 

 than the death-rate of married men and widowers. 

 From this fact we cannot reason as Dr. Stark has done 

 to a simple conclusion. All that we can do is to show 

 that one of three conclusions must be adopted : Either 

 matrimony is favourable (directly or indirectly) to 

 longevity, in a degree sufficient wholly to account for 

 the observed peculiarity ; or a principle of selection 

 the effect of which is such as, on the whole, to fill the 

 ranks of married men from among the healthier and 

 stronger portion of the community operates in a 

 sufficient degree to account wholly for the observed 

 death-rates; or lastly, the observed death-rates are 

 due to the combination, in some unknown proportion, 

 of the two causes just mentioned. 



No reasonable doubt can exist, as it seems to me, 

 that the third is the true conclusion to be drawn from 

 the evidence supplied by the mortality bills. Unfortu- 

 nately, the conclusion thus deduced is almost valueless, 



