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# 1.5 population structures

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### 1.5 population structures

1. 1. Population Structures By the end of this lesson you will: • Know what population structures are and how they are represented • Be able to calculate the dependency ratio • Have discussed the changing age-sex structure of the U.K • Considered the links between the D.T.M and agesex structures
2. 2. D.T.M essay • Intro – must always DEFINE the concept in the intro. • Every paragraph must have Point Explain Evidence and Link • Point = stating the fact, making a statement • Explain = This means that…’this shows that’…’in this sense’ • Evidence = Examples – statistics, relate to the stages and countries. • Link = ‘However’…show you are discussing. Use wording from the question. • Conclusion = conclude that the D.T.M is not that effective
3. 3. Exam Question • Distinguish between a refugee and an asylum seeker (2) • A refugee is defined by the UN as a person unable or unwilling to return to their homeland for fear of persecution. Whereas an Asylum Seeker is a refugee who formally applies to reside in a country when they arrive in that country.
4. 4. Population Structure • ‘The proportion of males and females in an area, usually in the form of age distribution’ • Usually represented in a population pyramid • Can show us many things; • The results of births minus deaths in specific age groups • The effects of migration • The effects of specific events • Q. How do you think we can deduce this information from the population pyramid?
5. 5. Age Structure • Age structures are particularly important • They can be measured in many ways • The dependency ratio (how many people are being supported) • The support ratio (how many people are supporting) • The juvenility index (how young is the population) • The old-age index (how old is the population) • Q. Why do you think age structure is particularly important?
6. 6. Population Pyramids Narrow base High Life Expectancy Parallel sides Declining BR Tall Disparity between sexes Narrowing base Impact of immigration Asymmetrical Small BR Bulge in males of 20-40 Small DR Study the population pyramids in your booklet. In pairs; match the element of the pyramid to the population structure on the pyramid
7. 7. Plotting a Pyramid 1) Look at the pyramid for UK 2001 2)Plot a population pyramid for Kenya using the statistics in the text book. Try to use a similar scale to the UK pyramid. 3)Label the two Pyramids: Wide base; narrow base; parallel sides; sloping sides; tall; short; 4) explain what each label shows about the country’s population. (BR, DR,LE, IMR, Growth)
8. 8. Spot the difference
9. 9. The changing age-sex structure of the UK • Where can you see slight bulges and indentations on the UKs population pyramid? • Read the information on pages 162-163 and give reasons for the following bulges and indentations: • 30s bulge • Large amount of people over 80 • The lower figures in the young ages Population pyramid video
10. 10. Less Developed Countries Youthful Populations • In these countries there are higher fertility rates (for reasons we have discussed) which leads to a larger base population. • The pyramid then tapers rapidly, indicating high mortality (again, due to reasons we have discussed) • Smaller proportions of elderly people are common • Predictions suggest that when the mortality rates drop, there will be problems created by the new larger groups of over-60s • Who will care for them after family members have migrated/died from diseases such as AIDS • Complete exercises 1-3
11. 11. Dependency Ratios • In the EU the dependent population is those people aged under 19 and over 60 • • • • • • • • • Country A has 2.5mill people between 0-19 5.2 people over 60 2.5+5.2 = 7.7 12mill people aged between 20-59 7.7/12 = 0.641 0.641 * 100 = 64 12/7.7 = 1.55 * 100 = 156 TASK: Calculate the dependency ratio Now calculate the support ratio
12. 12. Population Pyramids and Predictions • Although a pyramid gives you a snap shot of a country’s population at any one time – we can animate the pyramid to predict how the it will change in the future • This can then be used to make predictions about the population • The UKs population prediction is that there will be an increasing ageing population – the width of the bars for those in their 90s is significantly increased • The birth rate is predicted to stay at a similar level but fall slightly by 2050 • India, however, is going to have a different pyramid by 2050 to the UK • Answer A, B and C for population predictions
13. 13. Population Pyramids and the D.T.M • Each pair will be given a pyramid • Look at it and try and figure out what stage of the D.T.M this pyramid could represent • Make your comments and justify WHY on the sheet • Pass this around to the next pair and make changes if you see fit • Study figure 5.10 and complete activity 18 on page 166.
14. 14. High birth rate, rapid fall in each upward age group due to high death rate; short life expectancy
15. 15. High birth rate; fall in death rate so more middle aged people alive, slightly longer life expectancy
16. 16. Declining birth rate; low death rate; more people living to an older age
17. 17. Low birth rate; low death rate; higher dependency ratio; longer life expectancy
18. 18. Exam Question • Describe how the population structure of a country in stage 2 of the D.T.M is different from that of a country in stage 4 (5) • Countries in stage 2 will have a broad base, whereas in stage 4 this will be much narrower. In stage 2, it will taper rapidly towards the top, whilst in stage 4, the pyramid will be a similar width throughout and wider at the top than the stage 2 counterpart. The overall shape of the stage 2 pyramid may be seen as an expanding /progressive pyramid, whilst that of the stage 4 will be stable/contracting with an indent at the base.
19. 19. Homework • Jan 2012 – 5c • ‘Examine how population structure changes at different stages of the demographic transition’ • Complete your yellow population booklets up to page ____ • By next lesson, you should have covered: • Impact of migration on population structures • Ageing populations – Political, social, economic implications • Youthful populations – Political, Social, Economic implications