Dr. Salwa Tayel & Prof. Ashry Gad KSU Department of Family & Community Medicine

1. Dr. SalwaTayel & Prof. Ashry Gad KSU Department of Family & Community Medicine (December, 2013) DEMOGRAPHY: Population Pyramids

2. 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.

3. 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)

4. Three main elements of demography:1- Size of population (census) 2- Composition 3- Distribution Elements of Demography:

5. 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).

6. 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.

7. 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 areas with high migration or high seasonal mobility It is adopted in the majority of countries.

8. 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. Gives a factual figure Expensive More difficult and takes time adopted in U.S.A.

9. Inter-census estimate Population in inter-census years is estimated relying on “actual population” • Use the preceding census population as starting point • Adding the births and the immigrants • Subtracting the deaths and the emigrants

10. Mid Year Population • The population count is adjusted to represent the population as of July the 1st of the year • The mid year population is used to compute indicators related to population

11. Uses of population census • Provides information on the changes of population size • Population size is needed to compute morbidity, mortality and fertility rate • Related to “health status” of the population as it depends on the dynamic relationship between number of people, their characteristics and the space they occupy • Planning of health services is guided by demographic variables as number of health units required, their distribution and the number of healthcare workers required for service delivery

12. Population Pyramids

13. 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.

14. Population (in millions) Population (in millions) Male Female Age in years

15. Population pyramid is a graphical presentation of the age and sex composition of the population represented by two histograms (one for male and the second for female) of the age distribution of the population set at 5-year interval and placed back to back

16. Last Census data of Saudi Arabia (2010/1431) Population (total) 27.163.977Saudi 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%)

17. Apex= People living to old age People ≥ 60 years= Old dependency Side= mortality and migration Height= life span Median age People < 15 years= Young dependency Base= births

18. tion of males and females • Base: -Births; population adding to itself -Wide base reflects high births -Narrow base reflects low births • Apex: ldest people; reflects those living old age -Tapering apex reflects few living to old age -Broad apex reflects many living to old age • Height:-Life span; increase height reflects increase life span • Side: Change in population size due to death or migration, -Steep slope reflects rapid decrease,-Almost straight side reflects slow decrease

19. Less than 15 -Represents the size of people below 15 years <15 -Represents the size of dependent youth -Large size in rapidly growing population -Small size in slowly growing population • 60 + years -Represents the size of people ≥ 60 years -Represents the size of dependent old -Large size in population with longer life span -Small size in population with short life span • Median age:Age that divide the population into two halves -Small in population with high births -Large in population with low births

21. SAUDI POPULATION

22. Population 27 752 000 CBR 19 per 1000 population TFR 2.1 per woman Growth rate 1.5% CDR 3 per 1000 population Life expectancy 75 years Population 25 732 000 CBR 19 per 1000 population TFR 2.4 per woman Growth rate 1.5% CDR 3 per 1000 population Life expectancy 74 years

23. Population 31 877 000 CBR 17 per 1000 population TFR 2 per woman Growth rate 1.3% CDR 4 per 1000 population Life expectancy 77 years Population 40 251 000 CBR 13 per 1000 population TFR 2 per woman Growth rate 0.7% CDR 6 per 1000 population Life expectancy 81 years

24. Total population 27 752 316 Male population 15 105 575 Female population 12 646 741 Sex ratio (M/F) 119.4/100 Below 15 years 7 512 186 15 to < 60 years 18 802 626 ≥ 60 years 1 437 504 Young dependency ratio 39.95% Old dependency ratio 7.64% Total dependency 47.59%

26. 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 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.

27. Bases for Comparison: • Variation across age groups • Variations within each age group by sex

28. The importance of the population pyramids • 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: (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.

29. The importance of the population pyramids • 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.

30. 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).

31. 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.

32. Dependency Ratio

33. Compare the Structure of Population pyramids Source: Joseph A. McFalls, Jr. Population: A Lively Introduction. Population Bulletin 46(2); 1995: 22. Dr. Salwa Tayel Demography

34. Population Pyramid of Saudi Arabia 2009

35. 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_select.cfm?strISO3