Introduction to population pyramids

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<ul><li>1.Population Pyramids</li></ul> <p>2. Population Pyramids 3. What are Population Pyramids? </p> <ul><li>The population composition or structure of a country </li></ul> <ul><li>population pyramidorage-sex pyramid </li></ul> <p>4. Males and Females </p> <ul><li>Figures formalesare recorded on theleftof the diagram. </li></ul> <ul><li>Figures forfemalesare recorded on therightof the diagram. </li></ul> <p>5. Males and Females 6. Sex Ratio </p> <ul><li>The division between the sexes can also be analysed by calculating the</li></ul> <ul><li>male : female ratio </li></ul> <ul><li>or sex ratio </li></ul> <ul><li>This expresses the number of men in the population as a proportion of the number of women.</li></ul> <p>7. Horizontal Axis </p> <ul><li>The horizontal axis may either represent</li></ul> <ul><li>actual numbers </li></ul> <ul><li>OR</li></ul> <ul><li>the percentage of</li></ul> <ul><li>thetotal populationineach age category. </li></ul> <p>8. Actual Numbers 9. Percentage 10. Vertical Axis </p> <ul><li>The population is normally divided into five year groups e.g. 0-4, 5-9, 10-14 on the vertical axis.</li></ul> <ul><li>However, sometimes you will see one and ten year intervals too. </li></ul> <ul><li>The final years are collapsed into one category (e.g. 90+) </li></ul> <ul><li>Different age groups are known ascohorts </li></ul> <p>11. Five Year Cohorts 12. 13. Population PyramidsDeveloping Countries </p> <ul><li>Wide basewhich indicates a youthful population (as a result of high birth rates); </li></ul> <ul><li>Narrow top(there are fewer people in the older age groups because life expectancy is lower); </li></ul> <p>14. Sudan a typical developing country pyramid 15. Implications for governments in developing countries</p> <ul><li>Limited resourceswill be stretched to meet the needs of a large number ofdependent children for schooling, nutrition and health care; </li></ul> <ul><li>As this group reaches working age,a large number of jobs will needto be created to enable them to support themselves and their families. </li></ul> <ul><li>As this group reaches child-bearing age, it is likelythat fertility rates will be high , leading to continuedhigh rates of natural population increase. </li></ul> <p>16. Population PyramidsDeveloped Countries </p> <ul><li>Narrower base (due to lower birth rate) </li></ul> <ul><li>WHY LOWER BIRTH RATES? </li></ul> <ul><li>Wider top (reflecting a longer life expectancy) </li></ul> <ul><li>WHY A LONGER LIFE EXPECTANCY? </li></ul> <ul><li>In some developed countries there is a bulge in 40-45 age cohort as a result of the baby boomers of the 1960s </li></ul> <p>17. 18. Japan a typical developed country pyramid 19. An ageing population </p> <ul><li>The issues faced by many developed countries is of anageing populationwhere a smaller proportion of the population are of working age and are faced with the task of generating enough wealth to provide high levels of support for the elderly population.</li></ul> <p>20. Dependency Ratio </p> <ul><li>Theratioofnon-economically activetoeconomically activepeople in the population is called the dependency ratio. </li></ul> <p>21. Zero Population Growth </p> <ul><li>The population pyramid can also show zero-growth. </li></ul> <ul><li>This means thatbirth rates and death rates cancel each other out. </li></ul> <ul><li>In this case, the age-sex pyramid is more like acolumnthan a pyramid, and people are distributed evenly throughout the cohorts </li></ul> <p>22. 23. Developed and Developing Countries 24. Past, Present and Future Trends </p> <ul><li>As well as illustrating the effect of past changes, population pyramids can also indicate bothshort and long term future changesin population.</li></ul> <ul><li>We can use population pyramids to show the results ofmigration </li></ul> <p>25. Canada change over time 26. Characteristic of Population Pyramids - Summary </p> <ul><li>Awide basesuggests a high birth rate, a high proportion of young people and thus a rapidly growing population </li></ul> <ul><li>Anarrow basetells us that the birth rate has fallen </li></ul> <ul><li>Straight or near vertical sides tell us that the death rate is low </li></ul> <ul><li>Sides that narrow inwards from the bottomshow a high death rate </li></ul> <ul><li>Large numbers of males around 20-34 year groups suggest high rates of immigration. </li></ul> <ul><li>A small number of young people indicates high rates of outmigration </li></ul>


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