Demography 1

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Demography 1

Dr Paul T Francis, MD

Prof. Com MedCollege of Medicine, Zawia


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Demography

Demography is the scientific study

of human population

Demography studies 3 aspects of a

population

Changes in population size

Composition of population

Distribution of population in place


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Demographic processes

The demographic processes that

determine the size, composition

and distribution of a population are:

Fertility

Mortality

Marriage

Migration

Social mobility


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Sources of Demographic

information

Population census

Vital statistics

Migration

Before we plan any health interventionor programmes for the community we

should know the size and composition of

the community

We also need to know the changes that

will occur to the size and composition to

the population


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Demographic cycle

Population of all countries go

through the following stages

1ststageHigh stationary

2ndstageEarly expanding

3rdstageLate expanding

4thstageLow stationary

5thstageDeclining


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Demographic cycle

High stationary

There is high birth rate and high death

rate so the population remains

stationary. There is no increase or decrease in

the population


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Demographic cycle

Early expanding

Death rate begins to decline while

birth rate does not change

Many countries in Asia and Africa arein this stage


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Demographic cycle

Late expanding

The death rate declines further and

the birth rate also starts to decline.

Since the death rate is lower than birthrate the population keeps increasing

Some developing countries are in this

stage Libya is in this stage


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Demographic cycle

Low stationary

In this stage the death rate and the

birth rate are both low

So the population becomes stationaryagain

There is no increase or decrease in

the population


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Demographic cycle

Declining

In this stage the birth rate is lower

than the death rate

So the population starts to decline


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World population

About th of world population livesin the developing countries

China and India are the two most

populous countries in the worldThe world population growth rate

was at the peak in 1970

About 95% of the population growthis occurring in the developingcountries


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Life expectancy

Life expectancy is the average

number of years which a person of

a particular age may expect to live

It is one of the best indicators of a

countrys level of development andoverall health status

The life expectancy of people allover the world has been increasing


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Life expectancy at birth

In most countries the life

expectancy of women is more than

that of men

Life expectancy in Japan is the

highest 86 79

Life expectancy in USA is 80 76

Life expectancy in Libya is

75 70


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Fertility

FertilityIs the actual bearing ofchildren by a woman

The reproductive age of a woman is

between 1545 yearsSome factors affecting fertility are:

Age at marriage

Duration of married life Spacing of children

Education

Socioeconomic status


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Fertility

Birth rate =

Growth rate =Crude birth rateCrude death rate

Number of live births during the year

Estimated mid-year population

X 1000


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Demographic indicators of Libya

Crude Birth rate (1978) = 47.0

Crude Death rate (1978) = 5.1

Growth rate is 42/1000 = 4.2%

Total fertility rate (per woman) = 2.8


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Population structure of Libya

< 5 = 20.7%


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Summary

Study of population is important for

promoting health of population

The size and composition of the

population will help us plan forhealth interventions

Study of human population will help

us plan for the future health needsof a community.


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Demography 1

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