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AGEC 340 -- International Economic Development Course slides for week 4 (Feb. 2 & 4) Population growth and demographic transition*. What determines changes and differences in population growth, and in the proportion of people at each age?. - PowerPoint PPT Presentation
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AGEC 340 -- International Economic Development
Course slides for week 4 (Feb. 2 & 4)
Population growth and demographic transition*
• What determines changes and differences in population growth, and in the proportion of people at each age?
* If you’re following the textbook, this material is in Chapter 4.
Some terminology: Demography and economics
• The English language can be very confusing!
•When talking about…• “demography”: study of population, also the population itself• “population growth”: increasing number of people• “demographics”: measured characteristics of the population “
• But also…• the “economy”: the prod. & cons. activities of a population• “economic growth”: increases in prod. & cons. per person• “economics”: a way of studying the economy
Population Growth Over TimeOur Textbook Picture:
Population Growth Across Countries Our Textbook Picture:
Is population growth a problem……or an opportunity?
• Pop. growth lowers the amount of available land and other kinds of capital per person,
• …but it raises the total size of the economy, which may offer some benefits of scale:
more opportunity to specialize & trade more innovators with new ideas a larger market to cover fixed costs
• on balance, pop. size itself is not really bad;but changes during transition can be awful!
World Population Growth,More vs Less developed countries
Percent change from previous year
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
1951
1953
1955
1957
1959
1961
1963
1965
1967
1969
1971
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
Less Developed More Developed
Population data from the U.S. Bureau of the Census, International Data Baseretreived 4/21/05 from http://www.census.gov/ipc/www/idbnew.htmlin Online Demographic Aggregation
Prepared and copyright by Gene ShackmanThe Global Social Change Research Projecthttp://gsociology.icaap.orgCharts may be used freely.
Famine in China, 1958-1961:with quick catch-up afterwards!
Fast rise
Slow fall
meanwhile, in the richer countries
What drives population growth?
• The “demographic transition”:–population growth rates rise and then fall
…but what happens during the transition? –What initiates the change?–Do all countries follow the same path? –What determines the speed of change?
What happens during demographic transition? Our textbook picture is:
So what drives population growth is:
• The “demographic transition”:–population growth rates rise and then fall–driven by a decline in the death rate
– the “mortality transition”– followed by a decline in the birth rate
– the “fertility transition”
• Do all countries follow the same path?
Here’s the demographic transition for one specific country:
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
Crude Birth Rate (CBR): births per thousand people
Crude Death Rate (CDR):deaths per thousand people
what type of country is this? what caused these changes?
Each year’s “natural increase” in a populationis their total births minus total deaths
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
Crude Birth Rate (CBR): births per thousand people
Crude Death Rate (CDR):deaths per thousand people
How fast is population growth?
That was Sweden…
• Death rates began to fall after 1800– fell gradually from 25-30 per thousand– stopped falling at 10 per thousand in 1955
• Birth rates began to fall after 1825– fell gradually from 30-35 per thousand– reached death rate of 10 per thousand in
1980• Pop. growth went from 0.5 to 1.0 to zero pct./yr
And here it is again, in comparison with another country:
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
what type of country is this one?
The first country is Sweden… the second is Mauritius, an island off the coast of Africa
Population growth rates depend on both birth and death rates
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
Mauritius had very fast population growth after WWII, because of a very rapid decline in its death rate
How fast was Mauritius’s peak rate of population growth? When was it?
Fast mortality decline after WWII was driven by public health breakthroughs in many tropical countries
Reprinted from D.E. Bloom and J.G. Williamson, 1998. “Demographic Transitions and Economic Miracles in Emerging Asia.” World Bank Economic Review 12(3): 419-55.
…but now let’s compare Swedento a different country:
Sweden--Birth Rate
Sweden--Death Rate
Sources: Population Reference Bureau (www.prb.org). Underlying data are in 5-year intervals, from B.R. Mitchell, European Historical Statistics 1750-1970 (1976): table B6; Council of Europe, Recent Demographic Developments in Europe 2001 (2001): tables T3.1 and T4.1; CELADE, Boletin demografico 69 (2002): tables 4 and 7; F. Alba-Hernandez, La poblacion de Mexico (1976): 14; and UN Population Division, World Population Prospects: The 2002 Revision (2003): 326.
??--Birth Rate
??--Death Rate
Remember, population growth rates depend on both birth and death rates
Sweden--Birth Rate
Sweden--Death Rate
Sources: Population Reference Bureau (www.prb.org). Underlying data are in 5-year intervals, from B.R. Mitchell, European Historical Statistics 1750-1970 (1976): table B6; Council of Europe, Recent Demographic Developments in Europe 2001 (2001): tables T3.1 and T4.1; CELADE, Boletin demografico 69 (2002): tables 4 and 7; F. Alba-Hernandez, La poblacion de Mexico (1976): 14; and UN Population Division, World Population Prospects: The 2002 Revision (2003): 326.
??--Birth Rate
??--Death Rate
How did this country’s birth rate stay high for so long?How did that affect their population growth?
Africa’s demographic transition started late, and had a very high peak population growth rate
Source: Calculated from data in FAOStat (2007).
So what explains the historical mortality decline in today’s rich countries?
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
what kinds of disease are these? when were they reduced?
The first measles vaccine was introduced in 1968,
way after the disease stopped causing
many deaths
An example of mortality decline in the US
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
Within the U.S., whose mortality declined the most?
The 1918 flu epidemic was unusual in many ways:normally, mortality changed most for children
Another view of mortality by age
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
Great Britain
India
Niger
17th C. England
The HIV/AIDS epidemic is unusual in many ways: one complication is that it affects mainly adults
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
Great Britain
Botswana
Niger
17th C. England
The demographic transition involves both mortality and fertility
• Mortality rates fall due to better nutrition, public health conditions, medicines…
• What happens to fertility rates?–How high are the highest fertility rates?
biological maximum is around 12economic maximum is around 8-10
–How low are the lowest fertility rates? biological minimum is zeroreplacement fertility is around 2
Birth rates depend on both fertility (births/woman) and the number of women
© 2006 Population Reference Bureau
Worldwide
0.6
0.9
1.82.0 2.0
1.3
0
1
2
3
1950-1955 1970-1975 1990-1995 2010-2015 2030-2035 2045-2050
Bill
ion
s
0
1
2
3
4
5
6
Ch
ildre
n p
er
wo
man
Women 15 to 49 Average number of children per woman
Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.
Women of Childbearing Age and Fertility
Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005 Reprinted from Population Reference Bureau, 2007 World Population Datasheet. (www.prb.org)
Fertility rates don’t always fall!Average number of children
per
woman
1950–1955
1955–1960
1960–1965
1965–1970
1970–1975
1975–1980
1980–1985
1985–1990
1990–1995
1995–2000
2000–2005
0
2
4
6
8
10
Source: United Nations, World Population Prospects: The 2004 Revision, 2005. Reprinted from Population Reference Bureau (www.prb.org), 2007.
Uganda
Kenya
Colombia
South Korea
Fertility Trends in Selected Developing Countries, 1950-2005
…and they vary in rich countries too!
Source: National statistical agencies.. Reprinted from Population Reference Bureau, 2007 World Population Datasheet. (www.prb.org)
Fertility Trends in Europe and the United States: 1980-2006
The fertility transition is usuallyfrom 6-8 to 1-3 births per woman
• What can explain this regularity? • Why do the poor have more kids than the rich?
– why might they choose higher fertility on purpose?poorer women may have fewer other optionstheir children may be more valuable to them
poorer children start work at a younger age …and may help parents in old age or sickness
where child mortality is high, parents need to have many children to have some survive
– availability and ease of contraception matters too!
One explaination for fertility declineis lower infant mortality
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
Fertility decline versus infant mortalityacross countries
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
Fertility decline vs. infant mortality over time
Source: Montgomery, Keith (2000), “Notes on the Demographic Transition.” Available online at www.uwmc.uwc.edu/geography/Demotrans/demtran.htm.
The demographic transition affects more than population growth
• How does transition affect the mix of people?–Death rates fall mainly for children–Fertility rates fall later and more slowly
so the burst of population growth
takes the form of more surviving children
Demographic transition and age structure:your textbook “population pyramid”
Demographic transition and age structure:the population pyramid for Nigeria
1980
Reprinted from www.census.gov/ipc/www/idb.
Demographic transition and age structure:the population pyramid for Nigeria
2000
Reprinted from www.census.gov/ipc/www/idb.
Demographic transition and age structure:the population pyramid for Nigeria
2020
This helps explain your results from Exercise 1!
Reprinted from www.census.gov/ipc/www/idb.
Demographic transition and age structure:population pyramids for Indonesia
1980
Reprinted from www.census.gov/ipc/www/idb.
Indonesia has a much more “mature” population pyramid than Nigeria
Demographic transition and age structure:population pyramids for Indonesia
2000
Reprinted from www.census.gov/ipc/www/idb.
Indonesia has a much more “mature” population pyramid than Nigeria
Demographic transition and age structure:population pyramids for Indonesia
2020
Reprinted from www.census.gov/ipc/www/idb.
Indonesia has a much more “mature” population pyramid than Nigeria
Demographic transition and age structure:population pyramids for the United States
1980
Reprinted from www.census.gov/ipc/www/idb.
The population “ages”, but there arecontinued echoes of the post-WWII baby boom
Demographic transition and age structure:population pyramids for the United States
2000
Reprinted from www.census.gov/ipc/www/idb.
The population “ages”, but there arecontinued echoes of the post-WWII baby boom
Demographic transition and age structure:population pyramids for the United States
2020
Reprinted from www.census.gov/ipc/www/idb.
The population “ages”, but there arecontinued echoes of the post-WWII baby boom
Demographic transition and the age structure of the population
• During the demographic transition, when death rates fall before and faster than birth rates, – at first kids are an increasing share of the
population, so the “dependency ratio” rises– then kids are a decreasing proportion of
people, and the share who are working rises– eventually share who are elderly rises, and
the proportion who are working falls again
Source: UN Population Division, World Population Prospects: The 2000 Revision (http://esa.un.org/unpp)
Past and Projected Child Dependency
Changing age structure has a big influence on the economy
0
10
20
30
40
50
60
70
80
90
100
1950
1960
1970
1980
1990
2000
2010
2020
2030
2040
2050
No.
of c
hild
ren
(0-1
4)pe
r 10
0 ad
ults
(15
-59)
E. Asia S. Asia Sub-Sah. Africa Whole World
• The demographic transition to higher and then lower population growth rates…– starts with a decline in child mortality
due historically to better nutrition and living conditions, and then to medical intervention
– is completed by a decline in fertility due mainly to increased child survival,
increased investment in child’s education, reduced need for child’s work, and increases in mother’s other opportunities
In conclusion...
…demography is very important!
– in Europe death rates fell slowly, in response to slow improvements in standard of living;
– in Africa, Asia and Latin America, death rates fell quickly with sudden availability of vaccines, antibiotics and disease control after WWII
– so today’s poor countries have had much faster pop. growth and worse dependency ratios than Europe or America ever did
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