ABSTRACT
Like all subjects, demography has a language and a methodology of its own that has developed in response to the need for ways of describing the char acteristics of populations accurately and precisely. Over the years this has led to the establishment of a standard set of criteria for measuring such basic phenomena as fertility and mortality, and has provided a common frame of reference for the comparison of one population with another, or for assessing changes over time. The concepts of fertility and mortality are easy enough to grasp, but their precise definition and measurement require the use of analytical techniques which accommodate all the rele vant factors. For example, measures of fertility need to take into consideration not just the number of children being born but also the size of the total population, or more specifically the size of the reproductive age-group. Measurements can be further refined to take account of the variations in child-bearing across the reproductive age-range and the impact of female age-specific mortality rates — all of which help to provide a more detailed statistical estimate of the rate at which children are being added to the population. Some of the techniques used require fairly complex procedures and at first sight may seem daunting to those not experienced in statistical analysis. But in almost all cases the methods are based on simple princi ples and it is not always necessary to understand the mechanics of calculation in order to appreciate the meaning of the results.
