Associate Professor Family and Community Medicine Department King Saud University

1. Dr. Salwa Tayel Demography

2. DEMOGRAPHY By Dr. Salwa Tayel Associate Professor Family and Community Medicine Department King Saud University Dr. Salwa Tayel Demography

3. Learning objectives By the end of this lecture you will be able to: • Define demography • List elements of demography • Describe population pyramids • Compare between population pyramids of developed and developing countries. Dr. Salwa Tayel Demography

4. DEMOGRAPHY Demography is the science that studies human population. Demography: Is the statistical study of the characteristics of human populations, especially with reference to size and density, growth, distribution, migration and vital statistics, and the effect of all these on social and economic conditions. Dr. Salwa Tayel Demography

5. Three main elements:1- Size of population (census) 2- Composition 3- Distribution Elements of Demography: Dr. Salwa Tayel Demography

6. Population Census • The population size is determined by counting the inhabitants and their characteristics periodically. • This census is of importance for each country for planning purposes and is usually done every 10 years. • Sex, age, nationality, religion, occupation, marital status, level of education, economic characteristics etc. are investigated in the census. Dr. Salwa Tayel Demography

7. Types of Census: A. De Facto Enumeration: Counting all people in the locality where they are present at the time of the census irrespective of the person’s usual residence. De Facto census is economic procedure and much simpler But, moving people can be counted twice It is adopted in the majority of countries. Dr. Salwa Tayel Demography

8. Types of Census: B . De Jure Enumeration: Counting all people of locality according to their actual residence regardless of their actual location during census time. Expensive More difficult and takes time adopted in U.S.A. Dr. Salwa Tayel Demography

9. Demographic indicators for the year 2005 Census: 23,118,994Saudis: 16,854,154Non Saudis: 6,264,840Crude Birth Rate: 25.3/1000 population Crude Death Rate: 3.8/1000 population Dr. Salwa Tayel Demography

10. Population Pyramids Dr. Salwa Tayel Demography

11. 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 point in time. The shape of the pyramid reflects the major influences of births and deaths, in addition to any changes due to migration. Dr. Salwa Tayel Demography

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19. United States Population, 1995 Source: Joseph A. McFalls, Jr. Population: A Lively Introduction. Population Bulletin 46(2); 1995: 22. Dr. Salwa Tayel Demography

20. Factors affecting population Pyramids Factors that influence population include: • Fertility (births), • Mortality (deaths) and • Migration. Dr. Salwa Tayel Demography

21. Structure Of Population Pyramids • 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 a series of bars, each 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. Dr. Salwa Tayel Demography

22. Bases for Comparison: • Variation across age groups • Variations within each age group by sex Dr. Salwa Tayel Demography

23. From the shape of the pyramid the following can be learnt: • Sex ratio: Percentage of males and females. • Age structure: • Base denotes births (broad or narrow base) • Apex denotes elderly • Mortality and emigration: Shape of sides (sloping or steep). • Life expectancy: Height of the pyramid and shape of the apex. Dr. Salwa Tayel Demography

24. From the shape of the pyramid the following can be learnt: • 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. Dr. Salwa Tayel Demography

25. 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. Dr. Salwa Tayel Demography

26. Types of Dependency Ratio • Young dependency: Presented by the surface area below the horizontal line passing through 15 years of age. • Old dependency: Presented by the surface area above the horizontal line passing through 65 years of age. • Total dependency: Presented by the surface area below the horizontal line passing through 15 years of age and that above the horizontal line passing through 65 years of age Dr. Salwa Tayel Demography

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29. Bibliotheca Alexandrina Thank you Website http://faculty.ksu.edu.sa/73234/default.aspx salwatayel@hotmail.com Dr. Salwa Tayel Demography Dr. Salwa Tayel (Descriptive Studies) 29 24/10/2010