Much of the demographic research undertaken in this country is naturally concerned with statistics relating to the British nation. It is very desirable, however, that attention should also be directed abroad. As Prof. J. B. S. Haldane has recently said, ‘any branch of knowledge is improved by a background’; it follows that our understanding of the affairs of our own population can be increased by a study of the numbers and movements of people elsewhere. Theories formed in order to account for occurrences in one country may appear unreasonable when tested in the light of other population data. Alternatively, they may find useful confirmation; a good example is to be seen in W. S. Hocking's article in J.I.A. on the mortality of males in later middle life. By making international comparisons, not only did the author find valuable supporting evidence for his observations based on British data, but he was enabled to carry his analysis a stage further and examine the effects of differing degrees of industrialization upon the relative levels of male and female mortality.