Observation

The purpose of this chapter is to explain the fundamental nature of population analysis and to give an introduction to some of the necessary statistical methods. The object of study is the demographer's fellow creatures, and he has perforce to respect the rights of individuals and groups. Fully-controlled scientific experiments of the kind that are conducted in laboratories are out of the question. If inquiries become too inquisitorial they may well be rendered ineffective by refusals to respond, by evasions or by untruths. All the demographer can do is to observe the course of events from time to time, open as they are to many conflicting influences acting concurrently. He can be said to have access to ‘experimental situations’ in the sense that different populations can be studied at the same time, and the same population at different times, so that the effects of the intervention of different variables can be assessed. Nevertheless, interpretation of cause and effect, if this is at all possible, requires considerable skill and judgment, and there may be differences of opinion even between acknowledged experts. Above all, care is required, because it is all too easy to draw the wrong conclusions.

Objectives

The aim of analysis in demographic work is to identify and measure as precisely as possible the influences that underlie population changes. By so doing it is possible to deepen one's understanding of the variations observed in past experience, and also perhaps to arrive at a basis for the prediction of future trends. There must always, however, be some doubt about the chances that identified influences will continue to have effect in the years to come.