Population Pyramid

圖片參考：http://upload.wikimedia.org/wikipedia/commons/3/31/Afghanistan_population_pyramid_2005.png

1 The base shows how many baby (0-4) exists
2 The top shows how many very old people (80+) exists
3 The sides shows the structure of the population
For example, in the above picture, the bar on the upper is more narrow than the lower part, this means that there does not exist aging of population problem
(Since old people are not too much)
Types of population pyramid
Stationary pyramid - A population pyramid showing an unchanging pattern of fertility and mortality.
Expansive pyramid - A population pyramid showing a broad base, indicating a high proportion of children, a rapid rate of population growth, and a low proportion of older people.
Constrictive pyramid - A population pyramid showing lower numbers or percentages of younger people.
4
Population Pyramid can shows the Active Working Age Group ( which are defined as those under 15 (children who are in full time education and therefore unable to work) and those over 65 (those who have the option of being retired). We can use Population Pyramid to calculate the ratio of Active Working Age Group and the whole Population. If the value is high, then this society is highly competitive.
5
We see the bars (women 20-39 , children) and then we can calculate, averagely, for one women, how many children are born. If the value is too low or high, then the goverment need to make some policy.



2007-02-07 06:12:51 補充：
5.Women and ChildrenIf all women born a lot of children, then there is not enough food to support.If all women born 0 or 1 children, then the society will have aging of population problemin the future