Importance of Demography

Only available on StudyMode
  • Download(s) : 589
  • Published : July 16, 2012
Open Document
Text Preview
Demography
Demography is the statistical study of human populations and sub-populations. 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. Demographic analysis can be applied to whole societies or to groups defined by criteria such as education, nationality, religion and ethnicity. Institutionally, demography is usually considered a field of sociology, though there are a number of independent demography departments. Formal demography limits its object of study to the measurement of populations processes, while the broader field of social demography population studies also analyze the relationships between economic, social, cultural and biological processes influencing a population. •The crude birth rate, the annual number of live births per 1,000 people. •The general fertility rate, the annual number of live births per 1,000 women of childbearing age (often taken to be from 15 to 49 years old, but sometimes from 15 to 44). •age-specific fertility rates, the annual number of live births per 1,000 women in particular age groups (usually age 15-19, 20-24 etc.) •The crude death rate, the annual number of deaths per 1,000 people. •The infant mortality rate, the annual number of deaths of children less than 1 year old per 1,000 live births. •The expectation of life (or life expectancy), the number of years which an individual at a given age could expect to live at present mortality levels. •The total fertility rate, the number of live births per woman completing her reproductive life, if her childbearing at each age reflected current age-specific fertility rates. •The replacement level fertility, the average number of children a woman must have in order to replace herself with a daughter in the next generation. For example the replacement level fertility in the US is 2.11. This means that 100 women will bear 211 children, 103 of which will be females. About 3% of the alive female infants are expected to decease before they bear children, thus producing 100 women in the next generation.[3] •The gross reproduction rate, the number of daughters who would be born to a woman completing her reproductive life at current age-specific fertility rates. •The net reproduction ratio is the expected number of daughters, per newborn prospective mother, who may or may not survive to and through the ages of childbearing. •A stable population, one that has had constant crude birth and death rates for such a long period of time that the percentage of people in every age class remains constant, or equivalently, the population pyramid has an unchanging structure.[3] •A stationary population, one that is both stable and unchanging in size (the difference between crude birth rate and crude death rate is zero).[3] A stable population does not necessarily remain fixed in size. It can be expanding or shrinking.[3] Note that the crude death rate as defined above and applied to a whole population can give a misleading impression. For example, the number of deaths per 1,000 people can be higher for developed nations than in less-developed countries, despite standards of health being better in developed countries. This is because developed countries have proportionally more older people, who are more likely to die in a given year, so that the overall mortality rate can be higher even if the mortality rate at any given age is lower. A more complete picture of mortality is given by a life table which summarises mortality separately at each age. A life table is necessary to give a good estimate of life expectancy. The fertility rates can also give a misleading impression that a population is growing faster than it in fact is, because measurement of fertility rates only involves the...
tracking img