The Social and Political Context of Population Forecasting

The subject of forecasting abounds in paradoxes. All statistical data refer to the past, yet for purposes of action only the future counts, and there is no necessary connection between past and future. Thus forecasting is on the one hand impossible, on the other hand indispensable. The difficulty is greater for population forecasts in that they are demanded for half a century or more ahead, where economic and other forecasts need cover no more than one or two years into the future. Forecasts are needed for planning; plans are rarely for more than five years in the future; why does anyone want population forecasts for the next half century? Official forecasts are usually presented as alternative projections, among which the reader chooses; yet if the reader chooses that projection whose output numbers he prefers, then he might as well choose among a set of random numbers. Forecasts are often in error, yet there have been cases in which they were given with accuracy, and where they were disregarded: examples are declining school attendance and increasing pensioners. Any discussion of the social and political context of anything gives the impression of denigrating that thing. Our intention here is to show the importance of statistics and of forecasts, despite errors and misunderstandings

The Profile of Intercohort Increase

For tracing the growth of populations over past time a useful indicator is cohort size. While a cohort moves through time, and therefore cannot be counted in the same way as the population of any given moment, yet its size can be measured as births less deaths up to some intermediate age. This may be estimated from a series of censuses, without reference to vital statistics or other data. The technique is applied to the onset of the world wide population expansion that followed World War 11. In several Asian countries it took place in a single five-year period with a multiplication of earlier intercohort increases by as much as threefold. The jump occurred early in Burma, late in Indonesia, and suddenly in both of those countries; in India it was more gradual, so that the onset of the current population expansion is less sharply marked. Calculation also shows a corresponding discontinuity in the rate of population change after World War I in a number of countries, but of lesser magnitude. Insofar as one may speak of a population explosion occurring in the world today the method of intercohort increase identifies its date of onset as immediately after World War II

Economic Growth in the First World: Help or Hindrance to the Third World?

Many would hold the First World responsible for Third World poverty. Much was written about exploitation of their colonies by the metropolis, and it is worth quickly reviewing this and other more recent points of contention. These have included pushing the colonies towards specialization in the production of tropical raw materials, development of synthetic substitutes as the colonies became restless and then declared independence, handling of loans to the Third World, copyright and other means of protection of intellectual property, environmental protection. While differences between the First and Third Worlds along these lines persist and are still prominent in discussion, yet they may be less important than something quite different that is holding back the world's poor. That is the example that the First World sets in technology, and that the Third World strives to emulate. Large projects -- steel mills, aircraft factories, an elaborately automated textile industry, are not without their attractiveness to the elite of a poor country, as a sign that it is catching up, that it need not replicate the labor intensive aspects of the Industrial Revolution as it was played through in the West. Yet putting its scarce capital into these is a great deal short of optimum allocation from a social point of view. Plants built for show played no part in the success of Japan, Korea, and Taiwan since World War II; on the other hand they did play a part in the Iran of Shah Pahlevi, and led to the displacement of the forward-looking, westernizing Shah by the backward-looking Ayatollah Ruhollah Khomeini. How did the Shah accomplish this unintended outcome of his high-technology programs? He did it by devoting too little attention to the little people. He disposed of exceptionally large amounts of capital, but it was not enough to create employment opportunities for all at the level of technology to which he wanted to jump in one stride. Capital was far less available to Japan in the 1950s, but what it had it used to make labor productive -- starting with agriculture where as in any country a large part of the labor is located at the start of industrialization. By raising productivity across the board, encouraging artisan industry in the countryside and the city alike, rather than concentrating on a few high-tech labor-saving plants, East Asian countries could get their whole population into the act, and ultimately progress to a point that in many respects is ahead of the West. What we know from Iran, Algeria, Egypt, the Philippines, and to some extent Latin America is that concentration of production may more quickly attain the appearance of development, but the process is unstable. The rural population could be disregarded in Adam Smith's day, but in a time of easy communication and irrepressible politicians the majority refuse to wait their turn while watching a minority become ostentatiously rich

Understanding World Models

Computer models of the world system produce very different results, ranging from economic collapse and massive starvation in the 21st century to universal prosperity for double or triple the present world population. The strikingly different conclusions that arise make it urgent to compare them effectively with one another, and see what it is about them that produces such diverse policies. And even insofar as the policies are similar, one would like to know more about how they arise from the models. This paper suggests a line of analysis that permits comparison of properties among such models. It takes up two ways of seeing what is in a model in addition to examining its documentation: first, making alternative transparent models that check the partial results of the complex model; and, second, 'black-box' experiments leading to a truncated linear form of the complex model. These two methods of assessment are designed to replace most of the documentation, and to allow the user to understand more effectively what assumptions he commits himself to in using the model

Can Theory Improve Population Forecasts?

Scholarly work on population includes many mechanisms accounting for changes in the components of population: births, deaths, and migration. Very little of this is used by forecasters, or even referred to in the forecasting texts. The present review of the more promising theory and empirical reports in demographic journals has as its object their incorporation in forecasting techniques. Some of the theory relates population to variables pertaining to the economy, to technology, or to social change; to use such models would require forecasts of the independent variables of the models. We know much about how fertility depends on income, but until we can forecast income (say 20 years ahead) that relation tells nothing about future population. Some theory relates population to variables difficult to measure, like the utility of children. Other parts again, like the demographic transition, are of uncertain timing. Much of mathematical demography constitutes comparative statics, which are conditional, whereas the user of forecasts requires unconditional statements. The perspective of usefulness for forecasting provides an illuminating, if severe, review of contemporary population research

On Future Mortality

Population projection is the activity of demographers that is best known to the public. The record shows some successes, in which the projected population came close to the population that subsequently materialized, and some failures, in which the two were far apart. The accurate forecasting of population using nothing hut demographic data is impossible, but two things can be done: marginal improvements in accuracy can be made, and the accuracy likely to be attained can be estimated in advance. Since the future population of any area depends on the three components (future births, deaths, and migration) in a simple accounting identity, its forecasting comes down to forecasting these components. The present paper looks into the mortality component, examining past mortality on the basis of Canadian data for the period 1921 to 1981. The examination shows that which past interval one takes as the indication of the pace of future population improvement is the most important element of the forecast of mortality. One reason that this finding is useful is that it enables the range of uncertainty in future mortality to be estimated from the range within which the future life table falls when we assume the pace of improvement of various past periods. Application of the same principle to fertility and migration will enable a calculation to be made of the uncertainty of population projections. This broader matter will be developed in a paper shortly to appear

How Secure Is Social Security?

Sharply reduced rates of population and industrial growth have been projected for many of the developed nations in the 1980s. In economies that rely primarily on market mechanisms to redirect capital and labor from surplus to deficit areas, the problems of adjustment may be slow and socially costly. In the more centralized economies, increasing difficulties in determining investment allocations and inducing sectoral redistributions of a nearly constant or diminishing labor force may arise. The socioeconomic problems that flow from such changes in labor demands and supplies form the contextual background of the Manpower Analysis Task, which is striving to develop methods for analyzing and projecting the impacts of international, national, and regional population dynamics on labor supply, demand, and productivity in the more-developed nations. One subtask is examining the growing problem of rising social security costs in industrialized countries. In this paper, Nathan Keyfitz observes that the problem of rising costs is likely to remain a tense issue for another half century, until by 2035 the demographic contributor to these costs will have reached a maximum and will start to decline, as the baby boom cohorts begin to die off. Keyfitz concludes his essay with a call for learning from the lessons of European experiences. Work on this topic is being directed toward that goal in the Human Settlements and Services Area. Publications in the Manpower Analysis Task series are listed at the end of this paper

From Malthus to Sustainable Growth

Running parallel to the economic theory of development, from Adam Smith to the present, has been expression of concern, what may be called an ecological preoccupation, about the capacity of the planet to support the increasing human population and to withstand the operations humans were carrying out on it. For Malthus this focussed especially on limits to food supplies, for his successors on limits of other raw materials, most recently on the sensitive dynamics of the planet. At the start there was no problem of communication between the economic and the ecological side; the same scholars wrote on both and they could be consistent with themselves. But in the past two or three decades the two sides have diverged. It would be too much to say that a debate is going on, for a debate requires that each side answer the points raised by the other, and that does not seem to be happening. How can the conditions for debate be established, and the public understanding and democratic decision making advantages of a debate be secured. The simple answer is for each of economists and biologists to acknowledge the results of the other in the field of its expertise, and to build its theory around these. That may ultimately lead to an overall consensus formula for sustainable development. But with the amount of knowledge now at hand and for a considerable time in the future the best we can hope for is incremental steps towards sustainability that are at least in the right direction. Some ten such steps are suggested

Population and Development within the Ecosphere: A Bibliographic Essay

Biologists and intelligent lay writers are raising the alarm on what is coming if population continues to increase: exhaustion of soils and mass starvation, deterioration of the ecosphere to the point where it is not livable, or if not that then at the very best declining incomes and loss of the amenities and accomplishments to which this generation has become accustomed. On the other side neoclassical economics, that also has a lay following, provides optimistic comfort: with modern ingenuity, given scope and stimulus by the freeing of markets, all shortages will be overcome, all deterioration repaired. Not population, but artificial constraints on the market, are doing the damage. The present survey is concerned with the consequences of population change and takes for granted that once development occurs population will come under control

Reconciling Economic and Ecological Theory on Population

At one time economics and ecology said the same thing about population: beyond a certain moderate density an increment of population will be harmful. But in recent years neoclassical economics has diverged sharply from biology. Now if the administrator asks an economist of this persuasion whether promoting birth control is important he will get the answer "Not very"; if he asks a biologist he will get "Very important". The administrator is left to resolve a question that is too difficult for the scholars in the field. This puts an unprecedented ambiguity into the policy analysis of population. What is needed is a theoretical framework in which both disciplines are incorporated, so that there will be one recommendation only, rather than two that cancel one another out. The two papers presented are a first attempt at such a reconciliation. People are seen as living within an economy, and the economy is located within the ecosphere. Mediating between them is the culture, that both sets objectives for individuals and provides the technology by which they attain those objectives. On this theoretical approach the population is at the center of a succession of nested boxes representing the economy, the culture, and the environment. The papers work out some of the consequences of this approach. They recognize the flexibility of substitution under the price system, as well as the limits the environment sets on any possible economy