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# 1.5 population structures

## on Oct 14, 2013

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## 1.5 population structuresPresentation Transcript

• 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
• 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
• 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.
• 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?
• 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?
• 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
• 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)
• Spot the difference
• 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
• 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
• 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
• 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
• 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.
• High birth rate, rapid fall in each upward age group due to high death rate; short life expectancy
• High birth rate; fall in death rate so more middle aged people alive, slightly longer life expectancy
• Declining birth rate; low death rate; more people living to an older age
• Low birth rate; low death rate; higher dependency ratio; longer life expectancy
• 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.
• 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