AGE DISTRIBUTION OF THE FOREIGN BORN 79 from that of a non-migrating population. There is usually a much larger percentage of unattached adults in the prime of life, especially of men. The great bulk of immigrants consists of persons above 15 years of age, and a continuous stream of immigration into a country could not but result in the existence of a proportion of the population with an abnormal concentration in the age groups 20-45 and an abnormal deficiency in the groups ander 15 years. Now the comparative absence of children in any considerable section or community tends to be reflected very clearly in the attitude of that section both in respect to social conduct and public policy. A complete understanding of social movements and of public opinion as it expresses itself in social legislation in a new country such as ours cannot be attained without taking into account the important factor of abnormal age distribution, especially in sections where such large proportions of the population have arrived compara~ tively recently from overseas. Here, as in many other instances, the fields of the statis tician and of the political and social philosopher come together. To compensate for the small percentage of children among the immigrant population, both the British and foreign born show proportions very much larger than the Canadian born in the age groups from 25 to 45 years. Indeed, in all groups above 15 years the per- centages both male and female for the British born are greater than for the Canadian born, and the same holds true for the foreign born except at very advanced ages. After 45 years of age, however, the differences are not so great as in the four five-year age groups preceding 45, Thus the immigrant population, while marked by a smaller percentage of children, has the second important characteristic of an abnormally large proportion in the most active years of adult life. That also reflects itself in the outlook and enterprise of a population group, and is of equal importance with the comparative paucity of children in explaining many phases of life in those districts where considerable proportions of the population are new Canadians who have recently arrived from abroad. Enterprise may be directed to social or anti-social ends. A balanced population in respect of the proportion married and having families tends to keep the activities of adult manhood and womanhood in social channels. A population unbalanced in respect to age distribution, while capable of phenomenal pro- gress when its energies are directed along constructive lines, is peculiarly subject to anti- social action and may become a serious menace to the body politic of which it forms a part. Thus age distribution is important from two points of view. First, as was pointed out at the beginning, it is necessary as a means of correcting crude data before comparing two sections of a population of entirely different age structures, in respect to a given char- acteristic. For example, before legitimate comparison is possible, crude statistics as to crime for the Canadian born population and the foreign born must be adjusted. Crime is far more frequent at certain ages than at others, and allowance must be made when one group has an unduly large proportion of its numbers at the ages most marked by criminal tend- encies. Such corrections may be made with a great degree of accuracy, and that specific problem is dealt with in detail in a subsequent chapter. The second point of view from which age statistics are valuable is in helping to explain such differences in behaviour of two sections of the population as may be attributed solely to the absence of people of other ages in normal proportions. Twice as large a proportion of men between 20 and 40 years of age will mean a larger amount of crime in the community merely because of the numerical addition of a large percentage among whom the crime rate is greater. But the simple numerical correction would not be enough to account for the amount of crime which would actually occur in such a community. The mere fact of age distribution tends to increase the criminality of each one of those surplus men by reducing the influences combating crime emanating from the existence of numbers of younger and older people in a neighbourhood. Unfortunately the influence of this last aspect of age distribution is very difficult of measurement, but that its existence is real cannot be doubted. The four diagrams reveal another type of difference. The age distribution of males and females differs in the four charts. The normal distribution is for males to be slightly in excess of females in early childhood. The hich mortality rate among male children