In considering the size of the future population, a significant fact which emerges is that the abnormally low birthrates of 1935 have created a wave formation in the population age structure which, unless it is consciously or accidentally corrected, will repeat itself in approximate 27-year cycles of low numbers of women in child-bearing age groups and low birthrates. Thus a considerable degree of distortion in the age structure of the population may remain for a long time, causing varying stresses and strains on those parts of the economic and social structure which have to deal with the resulting rapid changes in rates of growth. Economic conditions, which are comparatively unpredictable, are an important influence on births, but relative economic conditions which are entirely unpredictable are an even more important influence on migration.

Economic booms and depressions do not affect all countries in the same way. A predominantly primary producing country such as New Zealand is likely to be harder hit by a fall in world prices than is a predominantly manufacturing country such as the United Kingdom. As a result, we find a tendency for population to flow back to the United Kingdom in times of world economic depression.

A significant effect of this from the point of view of the growth of New Zealand population is that under difficult economic conditions there is a tendency towards migration outflow at the very time when the birthrate tends to fall owing to delayed marriages.

It will be obvious that forecasts of future population involve an element of uncertainty. This is due on the one hand to incomplete knowledge of the psychological, physiological, political, and economic factors underlying changes in fertility, mortality, and migration levels, and on the other hand to the difficulty of accurately forecasting the future course of those factors which are understood.

The figures of projected population shown in the table below have been prepared by the Department of Statistics, but it should be understood that these projections merely show the effect of the assumptions, listed with the table on the future growth of the existing population. The assumptions, however, have been adopted only after careful studies of trends in the patterns of fertility, mortality, and migration and, in the light of available current information, are regarded as those most likely to produce realistic projections over the length of the projection period.

by John Victor Tuwhakahewa Baker, M.A., M.COM., D.P.A., Government Statistician, Wellington.

• The latest available figures of population, migration, vital statistics, etc., are published in the Monthly Abstract of Statistics. The New Zealand Official Yearbook, published annually, includes sections on population and vital statistics, but the most comprehensive review of the New Zealand population is given in the various volumes of the Population Census. Another publication that should be consulted, especially for migration figures, is the annual Report on the Population, Migration, and Building Statistics of New Zealand