Population studies
By A. Swaby-Burton, Contributor

THE GENERAL objectives for this module are as follows.

1. To develop in students an understanding of population issues with specific reference to the Caribbean.

2. To enable students to apply sociological concepts and simple statistical procedures to an understanding of population issues.

In this week's lesson, I will be introducing you to some basic concepts used in the study of population.

Crude birth rate, fertility rate; crude death rate; natural increase; infant mortality rate; life expectancy internal and international migration (immigration and emigration); population growth rate; dependency ratio.

Before addressing the terms above let me first define the term population. Population refers to the number of people who live in a given area. It is important to note that the student who studies population is concerned not only with the number of people in an area but also with the factors that may be causing their number to increase or decrease. These include such matters as the state of medicine and sanitation, the extent to which birth control is practised, and the availability of food and other resources.

CRUDE BIRTH RATE

The number of live births per 1,000 of the population. We refer to the birth rates as being crude rates because of their general character. Crude birth rates, for example, do not tell us what proportion of the population is male or female or what the age distribution of the population is. Where statistics are collected that relate to birth or death rates to the above categories, demographers speak to specific rather than crude rates. For example, age-specific death rates specify the proportions of a population dying per year in each age group.

If we wish to understand population patterns in any detail, the information provided by specific birth-rates is normally necessary. Crude birth rates, however, are useful for making overall comparisons between different groups, societies and regions.

FERTILITY RATE

Birth rates are an expression of the fertility of women. 'Fertility' refers to how many live-born children the average woman has. A fertility rate is quite a complex calculation. It is the number of children that would be born to an average woman in a given population if she were to live to the end of her child-bearing years and bear children at the same rate as those currently in the age group who have just passed the age of child-bearing.

CRUDE DEATH RATE

Also known as mortality rate is calculated in the same way as birth-rates; the number of deaths per 1,000 of the population per year. Like crude birth rates, crude death rates only provide a very general index of mortality (the number of deaths in a population). Specific death rates give more precise information.

INFANT MORTALITY RATE

A particularly important aspect of death rates is the infant mortality rate. The infant mortality rate is the number of babies per 1,000 live births in any year who die before reaching the age of one. One of the key factors underlying the population explosion has been the reduction in infant mortality rates.

LIFE EXPECTANCY

Declining rates of infant mortality are the most important influence on increasing life-expectancy, that is, the number of years the average person can expect to live.

MIGRATION

The movement of people into or out of a particular territory. Migration is sometimes involuntary, such as the forcible transportation of 10 million Africans to the Western Hemisphere as slaves (Sowell, 1981). Voluntary migration, however, is usually the result of complex 'push-pull' factors.

INTERNAL MIGRATION

The following are definitions of the more usual terms used in the study of internal migration.

IN-MIGRANT

A migrant who enters a particular community by crossing its boundary from some point outside of the community, but within the same nation. This is to be distinguished from the 'Immigrant' which refers to incoming international migrants.

OUT-MIGRANT

A migrant who departs from the particular area under observation by crossing its boundaries to live in a point outside, but within the same nation. This is distinguished from the term 'emigrant' which refers to outgoing international migrants.

NET BALANCE OF INTERNAL MIGRATION

The migration balance of a community or area consists of the number of in-migrants minus the number of out-migrants. The net balance may either be positive (representing the net gain to the community) or negative (representing a net loss).

LIFETIME MIGRATION

Lifetime migration is derived by classifying as internal migrants, all persons who changed their place of residence from one area to another within a country at any time during their lives. In practice, migrants who have returned to, and are enumerated in their place of birth, are usually excluded from the life-time migrants.

CURRENT MIGRATION

Current migration is migration that has taken place in some recent fixed period. For example during the past year, the past five-year period, the past decade etc. On this basis, any person who has changed his residence from one area to another during the specified period would be classified as an internal migrant. Persons born abroad and non-resident in the country could on this basis be classified as internal migrants if they have changed residence within the country: should be taken to indicate in each case whether immigrants are included in the classification.

DEPENDENCY RATIO

The number of dependent children and retired persons relative to productive age groups. (Coleman and Salt 1992).

Join me next week as I look at population theories.