Statistical study of human population. It can be a very general science that can be applied to any kind of dynamic human population, that is, one that changes over time or space. It encompasses the study of the size, structure and distribution of these populations, and spatial and/or temporal changes in them in response to birth, migration, aging and death.
Fertility - Refers to the actual no. of children born to a woman or group of women. A simple way to measure fertility is to get the crude birth rate: the numbered of registered birth’s per 1,000 of the population in a given area at a specified time.CBR= Registered number births in a yr. X 1,000 Total mid year population
Mortality. - refers to the no. of deaths per 1,000 of the total mid-year population in a particular place at a specified time, and is measured by the crude death rate.CBR= Registered number of death a yr. X 1,000 Total mid-year populationLife Expectancy – refers to the average number of years a person can expect to live at the time of birth.
Migration – another factor w/c affects population change. Push – refers to the unfavorable, unattractive condition which impel a person or group of persons to move at an area. Natural Disasters – such as famines, floods or volcanic eruption, political repressions; religious or racial discrimination or persecution; or internal disorders such as war and other forms of conflict.
Pull – refers to the favorable condition orattractions of a locality which lure a person orgroup of persons to move in to that area. Amongthese are favorable climate, employmentopportunities, peace and order, political andreligious freedoms, respect for human rights, betterrecreational & cultural facilities.Internal Migration – is the spatial movement ofa person or groups of persons within a country orspecified territory, more or less for permanentresidency.
Immigration – when one enters the country of destination.Emigration – when one leave’s one country in order to move into another.
Overall the world’s popular grew slowly untilabout 1850 – so slowly, in fact the severalhundred thousand years were needed for the earthto reach one billion ( Wilford, 1981). The earth’ssecond billion were added by 1930 due toadvances in medicine, farming transportation.Population is estimated to cross the 6 billionthresholds in October 1999.
Malthusian Theory – the English scholar Thomas Maltus (1766 – 1834) whose theories appeared in 1798 in “An Essay on the Principle of Population”, theorized pessimistically that population was uncontrollable and that it would, at a future date, reach and then exceed a level at which the planet could sustain in incredible high population numbers.
Demographic Transition Theory – the concept demographic transition refers to the three char. stages of the population dynamics for societies under going industrialization. In the first stage, which is character of preindustrial societies both the birth rate and the death rate are high and relatively stable. The second stage is a transitional one, the birth rate remains but the death rate declines as nutrition, health and sanitation improve. Stage three, both the birth rate and the death rate are low and in balance again.