The elements of population are size, composition and distribution. Size is measured through census or official count of people and their relevant characteristics such as age, sex and occupation. Composition refers to the distribution of a population in various categories like age orsex.Composition can be measured by such terms as the sex ratio, the median age, the dependency ratio and the population pyramid, a pictorial representation of the age and sex distribution of the population of an area.

What are the three processes that affect population size

? Three processes that affect population size are fertility, mortality and migration. Fertility refers to the frequency of births in a population and its study includes crude birthrate, age at marriage, use of contraceptive, societal attitudes toward family size, infanticide and abortion but fertility is distinguished from fecundity or the potential number of children that the women of a population could produce. Mortality is measured in a crude mortality rate, an age-specific mortality rate, a life expectancy at birth rate and an infant mortality rate. Studying migration includes counting the emigrants and immigrants in order to find a crude migration rate.

What is the Malthusian theory?

Malthus believed that population without any external controls will double once every generation until the uppermost level of subsistence will not support the population size at which time preventive checks will come into play.

What is the demographic transition?

The demographic transition is the pattern populations follow as their nations develop from an agricultural base to an industrial one. Stage one has high birth and death rates. Stage two has a high birth rate and lower death rate. In stage three the birth rate falls, bringing about a stable population size again.

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