Transcript Lecture 22-Demography Concepts and Popularion

DEMOGRAPHY:
Population Pyramids
Dr. Salwa Tayel & Prof. Ashry Gad
KSU Department of Family & Community Medicine
(December, 2014)
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OBJECTIVES OF THE LECTURE
By the end of this lecture students will be able to:
• Define demography
• List elements of demography
• Describe population pyramids
• Compare between population pyramids of developed and
developing countries.
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Definition of Demography
 Demography is the science that studies human
population.
 Demography: The study of populations, especially with
reference to size and density, fertility, mortality, growth,
age distribution, migration, and vital statistics, and the
interaction of all these with social and economic
conditions. (Oxford Dictionary)
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Elements of Demography:
Three main elements of demography:
1- Size of population (census)
2- Composition
3- Distribution
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Population Census
• The population size is determined by counting the
inhabitants and their characteristics periodically.
• Census enumeration of a population usually
records identity of all persons in every place of
residence, with age or birth date, sex, occupation,
national origin, language, religion, marital status,
income, educational level (or literacy).
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Population Census
• Census data is of importance for every country
for planning purposes and is usually done every
10 years.
• The population size in inter-censal years (years
between each census) is estimated from births,
deaths and net migration.
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Types of Census:
A. De Facto Enumeration:
Counting all people in the locality according to their
location at the time of enumeration irrespective
of the person’s usual residence.
De Facto census is:
economic procedure and simple
But, moving people can be counted twice
It is adopted in the majority of countries.
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Types of Census:
B . De Jure Enumeration:
A de jure census assigns persons according to
their usual place of residence at the time of
enumeration.
Expensive
More difficult and takes time
adopted in U.S.A.
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Last Census data of Saudi Arabia
(2010G /1431H)
Population (total) 27.163.977
Saudi 18.707.576
Males 9.527.173 (50.9%)
Females 9.180.403 (49.1%)
Non-Saudi 8.429.401
Males 5.932.974 (70.4%)
Females 2.496.427 (29.6%)
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Estimated population Saudi
Arabia (2012)
Total Population 29,195,895
Saudi: 19,844,632
Non-Saudi: 9,351,263
% of the Saudi Population of Total Population
% of non Saudi Population of Total Population
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67.97%
32.03%
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Population Pyramids
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POPULATION PYRAMIDS:
THE AGE-SEX COMPOSTION OF POPULATIONS
Population pyramid is the graphical presentation of the
age and sex composition of a population of an area
or country at a certain point in time.
The shape of the pyramid reflects the major influences
of births and deaths, in addition to any changes due
to migration.
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Structure of Population Pyramid
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Structure of Population pyramid
The right half for females
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Structure of Population pyramid
Rotated Bar graph for age distribution of females
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Structure of Population pyramid
Bar graph for age distribution of females
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Structure of Population pyramid
Bar graph for age distribution of males
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Structure of Population pyramid
Both bar graphs are rotated and put back to back
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Structure of Population pyramid
• Sex
– Males are shown on the left side of the pyramid
– Females on the right
• Age
– young persons at the bottom, and
– the elderly at the top.
• The pyramid consists of series of bars, each is drawn
proportionately to represent the percentage contribution of each
age - sex group
• (often in five-year groupings) to the total population
• The total area of the bars represents 100 per cent of the
population.
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Bases for Comparison:
1) Variation across age groups
2) Variations within each age group by sex
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The importance of the population pyramids
1. Sex ratio: Percentage of males and females.
2. Age structure:
– Base denotes births (broad or narrow base)
– Apex denotes elderly
3. Mortality and emigration:
Shape of sides (sloping or steep).
4. Life expectancy: (Average number of years that a
newborn is expected to live if current mortality
rates continue to apply)
Height of the pyramid and shape of the apex.
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The importance of the population pyramids
5. Median Age: (lower or higher)
The point in the vertical axis of age through which passes
the horizontal line that divides the surface area of the
pyramid into two equal parts (50%) younger and 50%
older).
The position of this defined point is inversely related to the
width of the base.
The wider the base, (i.e. the higher the birth rate), the lower
the median age and vice versa.
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The importance of the population pyramids
6. Dependency Ratio
• The Dependency ratio describes the relation
between the potentially self-supporting portion of the
population and
• the dependent portions at the extreme of age (below
15 and above 65).
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Types of Dependency Ratio
•
•
•
Young dependency: Proportion of population
below 15 years of age.
Old dependency: Proportion of population above
65 years of age.
Total dependency: Proportion of population below
15 years of age plus the proportion of population
above 65 years of age.
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Dependency Ratio
Young dependencyratio 
Old .dependency.ratio 
Populationbelow 15 years
Populationaged between 15  65 years
Population above 65 years
Population between 15  65 years
X 100
X 100
Total dependencyratio 
Populationbelow15 years  those above 65 years
Populationaged between15  65 years
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X 100
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Demographic Data of Saudi Arabia
(2012)
• Life expectancy at birth
both sexes 73.8 years (Female 75.2 Male 72.8)
• Average Saudi Population Growth Rate 3.19%
• Percentage of Population under 5 (%) 10.85
• Percentage of Population under 15 (%) 30.37
• Percentage of Population 15-64 (%) 66.89
• Percentage of Population over 65 (%) 2.73
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Compare the Structure of Population pyramids
Source: Joseph A. McFalls, Jr. Population: A Lively Introduction.
Population Bulletin 46(2); 1995: 22.
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References
• Last JM, editor. Dictionary of epidemiology. 4th
ed. New York: Oxford University Press; 2001
• World Health Statistics 2011. Indicator compendium.
Indicator Code Book. World Health Statistics - World
Health Statistics indicators
• Core Health Indicators, Health indicators WHO.
Available at:
http://apps.who.int/whosis/database/core/core_sel
ect.cfm?strISO3
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