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BY DR: MUHAMMED NAJEEBAssist: Professor
Community Medicine Deptt: LUMHSJamshoro Sind, PAKISTANE mail mnajeeb80@gmail.com
DEMOGRAPHY
POPULATION PYRAMIDS
Pictorial presentation of 3 Factors (Influence Population)Births
DeathsMigration
Features (Population Pyramids)
In terms of its composition by:- Age, Sex Males (on Left side) Females (on Right side) Children (at bottom) Elders (at Top) Adjoining bars (contribution of each age, Sex group)
Developing Country (Pakistan)
Base: Broad (High Birth rate)Top: Narrow / Acute apex (No: of Elders (Less)
High Dependency rate Bad effect (on Economy) Unproductive (Half Pop) Under 15 Ys: ---- 44% Pop: B/w 15- 64 Ys: 52% Pop:
Developed Countries (Sweden)
Base: Narrow (Low Birth rate)Middle: Bulge (Convex border)Top: Obtuse apex (More Elders)
Low Dependency rate Good effect (on Economy) Productive ( More than Half Pop) Under 15 Ys: ---- 25% Pop: Above 15 Ys: ---- 75% Pop:
EXAMPLE
PAKISTAN
DEMOGRAPHIC CHARACTERISTICS
Population unevenly distributed with
All countries in region have a positive rate of natural population change.
very densely populated areas
very sparsely populated areas.
1.
DEMOGRAPHIC TRANSITION
Growth Rate (%) Grading of population increase
0 ( Zero)
0 to 0.5
0.5 to 1
1 to 1.5
1.5 to 2.0
> 2
Stationary Growth (No Growth)
Slow Growth
Moderate Growth
Rapid Growth
Very Rapid Growth
Explosive Growth ( Population explosion) OR Population Bomb
Two demographic worldsLess-developed counties represent 80% of the world population, but more than 90% of projected growthRicher countries tend to have negative growth rates.
DEMOGRAPHIC TRANSITION 3 TYPES
1. Old balance Fertility Mortality
2. New balance Fertility Mortality
3. ImbalanceFertility Mortality
India in 1920-1930
Many countries of S. Asia & Africa
China,SingapurPak in 1970
Germany,Hungary (after effect of II world war)
DEMOGRAPHIC CYCLE
PopulationGrows slowly
PopulationGrows rapidly
PopulationBecomes stationaryPopulation
stationary
Populationdeclines
15
Demographic Transition AccompanyingEconomic and Social Development
BBirth Rate
Death Rate
Note that in English, fertility refers to actual births.
Fecundity refers to the biological ability to have children (the opposite of sterility).
Dependency Ratio
The dependency ratio tells us how many young people (under 16) and older people (over 64) depend on people of working age (16 to 64). The dependency ratio is worked out with this formula.
Dependency Ratio = % under 15 + % over 65 ys: X 100 % between 15 & 64
A worked example should make this clearer. Pakistan, which is a developing country, has 41% of its population less than 15, and 4% over 65. This makes 55% (100 - (41+4)) between the ages of 15 and 64.
Dependency Ratio = 41 + 4 X 100 = 81.8 55
END
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