Pre Marital Sex

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DEMOGRAPHIC TERMS
Keith Montgomery 
Department of Geography and Geology
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In order to fully understand the demographic transition there are some terms and concepts we should know. The following terms are defined and discussed below:   
Birth rate 
Death rate 
Natural change 
Fertility 
Replacement fertility| Doubling time 
Survivorship curve 
Population pyramid 
Population momentum|
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Birth Rate:
The Crude Birth Rate represents births in a given year for every 1000 persons. By expressing births in this manner we can compare countries of greatly differing populations. For example, in The United States there were a total of 3.78m births in 1998. Given a total population of 270mthe rate of birth was therefore 14/1000. In Guatemala, on the other hand, there were a total of 0.43m births in 1998. However, given a total population of only 12m, this represents a rate of birth of 36/1000 -- a much higher rate than that of The United States, as we might expect. Strictly speaking this is a "crude" rate of birth because it is averaged across the entire population, regardless of age or sex! And neither is it adjusted for the age structure of the population. Thanks to the post-war "baby boom", 25% of the US population is female and in childbearing years, compared to 23% in Guatemala. More specifically, then, for every 1000 women of childbearing age (15-49 yrs) in Guatemala there were 153 births in 1998, compared to 54 in The United States -- this is an even greater contrast in reproduction than crude birth rates alone indicate, and this is so because there are relatively less women of childbearing age in the Guatemalan population . This measure of birth rate is also sometimes called the "general fertility rate" or the "age-specific birth rate". Nevertheless, it is the Crude Birth Rate that is most commonly quoted and compared and this is the figure we will use. The CBR is controlled mainly by the fertility of the population (see below) and by the number of women of childbearing age in the population (see population pyramid below). -------------------------------------------------

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Death Rate:
The Crude Death Rate represents deaths in a given year per 1000 people. By expressing deaths in this manner we can compare countries of greatly differing populations. For example in The United States there were a total of 2.43m deaths in 1998. Given a total population of 270m the rate of death was therefore 9/1000. In Guatemala, on the other hand, there were a total of 0.08m deaths (80,000) deaths in 1998. However, given a total population of 12m, this represents a rate of death of 7/1000 -- perhaps surspisingly, a lower rate than that of The United States. However,  this is a "crude" rate of death because it is averaged across the entire population, regardless of age (or sex, or ethnicity). Clearly, for example, one's chances of dying in The United States are considerably more or less than 1% depending on whether one is 90 yrs old or 9 yrs old! Or whether one is a white male or a black male. And neither is it adjusted for the age structure of the population. This is the key to understanding how a Third World country can have a lower death rate than a developed country (not all do). In the US, 9.5% of the population is elderly (>65 yrs), whereas in Guatemala only 3.1% are over 65 yrs. thanks to recent growth and declines in childhood mortaility. So, although childhood mortality is still higher in Guatemala, the much higher proportion of young persons still resulted in relatively fewer deaths in 1998 (63% of Guatemala's population is less than 25 yrs, compared to 35% in The United States). The issue of age structure becomes all the more interesting if we compare population over time. In 1940 the CDR of the US was about 10.8. In 1998 it stood at...
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