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The Formula
In this chapter you will learn how financial, educational, spiritual, cultural, and emotional social forces shape and form the demographic trends within a society. You'll also get a glimpse of how demographic forces shape your society. The core of demographic studies has three component concerns: births, deaths, and migration. All of demography can be reduced to this very simple formula:
(Births-Deaths) +/- ((In-Migration)-(Out Migration))=Population Change.
This part of the formula, (Births-Deaths) is called Natural increase, or all births minus all the deaths in a given population over a given time period. The other part of the formula, ((In-Migration)-(Out Migration)) is called Net Migration which is all the in-migration minus all the out-migration in a given population over a given time period. Population Change is then added to a previous year's population to yield new population estimate. Most official population counts really are estimates. There are mistakes in counting that render results that are close, but never perfectly accurate.
Let's consider this formula by first looking at the US population in 1990. Census Enumerationis the formal counting of a population by its government. Based on the US Census, the US population was 248,709,000 (retrieved 7 April, 2009 from http://www.census.gov/main/www/cen1990.html ). If you start the estimate with the 1990 population, you can run the numbers through the formula and derive an end of year 1999 population estimate. You can see the results of adding all the US birth, death, and migration data for 1990-1999 in Table 1 below.
Table 1. Numbers of Births, Deaths, and Net Migrationa for the United States between 1990-1999b
| Births | - Deaths | + Net Migration | = Population Change |
| 39,860,000 | 22,711,000 | 9,580,000 | +26,729,000 |
a Net Migration=(In-Migration)-(Out-Migration) or (9,800,000)-(220,000)=(9,580,000)
b Data collected from two sources retrieved 7 April, 2009: Martin, P. & Midgley, E. (2003) "Immigration: Shaping and Reshaping America," Vol. 58, No. 2 Population Bulletin from www.prb.org; and www.census.gov Table 77. Live Births, Deaths, Marriages, and Divorces: 1960-2006.
By the end of 1999 the population was estimated to be (1990)+(1990-1999 population change)=1999 population or (248,709,000)+(26,729,000)=275,438,000. These estimates are very close to the actual July 1st, 1999 US Census estimates (retrieved 7 April, 2009 from http://www.michigan.gov/documents/9099usstreg_26029_7.pdf US POPULATION 1790-2000).
Table 2 lists the 10 most populated countries of the world in 2008 and the US ranks 3rd in 2008. The US is one of the most populated nations of the world and is estimated to continue to rank 3rd even in 2050. Interestingly, in 2050, India will rank 1st and China 2nd (see Table 3 for the details).
Table 2. The Ten Most Populated Countries in the World, 2008*
| Country | Estimated Population | |
| China | 1,324,700,000 | |
| India | 1,149,300,000 | |
| United States | 304,500,000 | |
| Indonesia | 239,900,000 | |
| Brazil | 195,100,000 | |
| Pakistan | 172,800,000 | |
| Nigeria | 148,100,000 | |
| Bangladesh | 147,300,000 | |
| Russia | 141,900,000 | |
| Japan | 127,700,000 |
Retrieved 7 April, 2009 from http://www.prb.org/pdf08/08WPDS_Eng.pdf
Table 3. The Ten Most Populated Countries in the World, 2050*
| Country | Estimated Population | |
| India | 1,755,200,000 | |
| China | 1,437,000,000 | |
| United States | 438,200,000 | |
| Indonesia | 343,100,000 | |
| Pakistan | 295,200,000 | |
| Nigeria | 282,200,000 | |
| Brazil | 259,800,000 | |
| Bangladesh | 215,100,000 | |
| Congo, De. Rep. | 189,300,000 | |
| Philippines | 150,100,000 |
Retrieved 7 April, 2009 from http://www.prb.org/pdf08/08WPDS_Eng.pdf
Date: 2015-02-28; view: 1229
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