STATISTICAL COMPARISONS. 469 



with such figures, the point is not without practical importance. 

 I have seen arguments at home, for instance, in which the 

 attempt has been made to prove the superiority of Austi'aUans 

 to the people of the United Kingdom in respect of health by 

 means of statistics of the general rate of mortality among the 

 two populations, no account being taken of the different distri- 

 bution of tW populations according to age. The comparisons I 

 have in my mmd failed on anothar point, being based upon a 

 hypothesis as to the connection between mortality rates and 

 the sickness of a population which had not been proved to be 

 true generally ; but even if the hypothesis had been generally 

 true, the neglect of the point of distribution according to age 

 made it entirely misleading. 



MORTALITY STATISTICS. 



I pass on to other statistics. Eeference has already been 

 made to mortality statistics in connection with the special point 

 of the constitution of populations according to age, but there 

 are many other traps in using such statistics for a comparison 

 between nations. The mere question of how the deaths are 

 recorded, and along with that the births, as far as many in- 

 ferencesfrom the mortality statistics are concerned, here becomes 

 important. Before the statistics of two countries can be com- 

 pared there must be a certainty that the registration process as 

 to numbers is effective and complete in each. This is not the 

 case in all countries, and it is an especially important matter in 

 historical investigations even in the same country ; the registra- 

 tion of births and deaths in England for instance being 

 notoriously deficient until a comparatively modern period. 

 Even a great country like the United States is still most 

 deficient in this vital particular ; there is no such thing as a 

 good birth and death rate for that great country. In 

 Philadelphia some years ago a local report of the registrar of 

 births, deaths, and marriages was put into my hands from 

 which it appeared that the deaths exceeded the births. 1 learnt 

 on inquiry that the explanation of a fact which would have 

 been somewhat startling if true was simply the neglect of the 

 laws or administration in the matter of the registration of births. 

 I do not know whether there has been improvement since in 

 this particular city of the United States, but that there is still a 

 lack of a uniform and effective system of registration throughout 

 the country is most certain. It is necessary then to reiterate again 

 and again the necessity for the utmost caution in the use of 

 such common figures as birth and death rates. Always when a 

 writer would make a comparison, let him see that his facts are 

 really the same. He must not be content to take them from a 

 dictionary without inquiring. 



These remarks hold good of other comj^arisons sometimes 

 made, particularly the prevalence of certain kinds of disease. I 

 need not say to an audience of experts what difficulties arise in 

 the definition of disease, and how doctors, apart from mistakes 

 as to what the disease really is of which a man dies, may 

 honestly vary in their statement of the fact from the number 



