5.5.1 DEMOGRAPHY DEFINITION
Thompson (2007) :
“The study of human populations – their size, composition and distribution across place – and the process through which populations change – Births, Deaths and Migration.”
Weeks (1994) :
“The science of population – concerned with virtually everything that influences, or can be influenced by population size, distribution, processes, structure, or characteristics.”
5.5.1.1 WHY STUDY DEMOGRAPHY
To understand why the populations of some countries are growing and why some are not
What happens to societies as their pattern of birth, death or migration change
Understanding all these consequences of population change (either growth or decline)
5.5.1.2 SOURCES OF DEMOGRAPHIC DATA
The kind of information we often seek for are:
i.
Population size and distribution
ii.
Population processes (fertility, mortality, and migration).
iii.
Population structure and characteristics
Three major sources of information for these three population processes are:
a)
Census
Information about persons – age, sex, marital status, source of livelihood, place of birth, number of children ever born, etc. Information can be found in official government reports.
b) Registration of Vital Statistics
Information about events – vital events and their rates are called vital rates – birth and deaths. - Vital registration – marriage, divorce, adoptions, fetal deaths as well as migration
c)
Sample Surveys
-
This method produces the same kinds of information and often much more detailed – based on a small sample rather than on the whole population – a sample of the population. -
Sample permits a lower total cost and a greater emphasis on the accuracy of the information about each individual.
