Topic: Calculating
Population
Aim: In What Ways
Can Demographers
Measure Population?
• Population Density: can be computed in up to three ways for a
place.
1. Arithmetic Density
– Total number of objects in an area
– Computation: Divide the population by the land area
2. Physiological Density
– Number of people supported by a unit area of arable land
– Computation: Divide the population by the arable land area
3. Agricultural Density
– Ratio of the number of farmers to amount of arable land
– Computation: Divide the population of farmers by the arable
land area
Arithmetic (Population) Density:
•Total number of people divided by total land area- used to
compare conditions in different countries
I.E. - For the United States, we would divide 300 million (# of
people) by 3.7 million square miles. The result shows the that U.S. has
an arithmetic (or population) density of 80 persons per square mile.
A street in Hong Kong, one of the most densely-populated
places in the world.
A street in Ulan Bator, Mongolia - the least densely-populated
country in the world
ARITHMETIC DENSITY Geographers rely on the arithmetic density to
compare conditions in different countries because the two pieces of
information–total population and total land area–are easy to obtain. The
highest arithmetic densities are found in Asia, Europe, and Central
America. The lowest are in North and South America and South Pacific.
Physiological Density:
• The number of people supported by a unit area of arable
(farmable) land.
• The higher the physiological density, the greater the
pressure on the land to produce sufficient food
• Reveals the relationship between size of a population and
the availability of resources in a region.
PHYSIOLOGICAL DENSITY Physiological density provides insights into the
relationship between the size of a population and the availability of resources in a region.
The relatively large physiological densities of Egypt and the Netherlands demonstrates
that crops grown on a hectare of land in these two countries must feed far more people
than in the United States or Canada, which have much lower physiological densities. The
highest physiological densities are found in Asia, sub-Saharan Africa, and South America.
The lowest are in North America, Europe, and South Pacific.
Physiologic
Population
Density
Luxor, Egypt
Egypt’s arable lands are
along the Nile River
Valley.
Moving away from the
river a few blocks, the land
becomes sandy and windsculpted.
Agricultural Density:
• Two countries can have similar
physiological densities, but they
may produce significantly
different amounts of food
because of different economic
conditions.
• Agricultural density is the ratio
of the number of farmers to
the amount of arable land.
• The Netherlands has a much
higher physiological density than
does India but a much lower
agricultural density.
AGRICULTURAL DENSITY The highest agricultural densities
are found in Asia and sub-Saharan Africa. The lowest are in North
America, Europe, and South Pacific.
Components of
Population
Growth
Why Is Global Population Increasing?
• Components of Population Growth
– Natural Increase
• About 82 million people are added to the population of the
world annually.
• Rate of natural increase affects the doubling time– number of years
needed to double the population, assuming a constant rate of
natural increase.
– Twenty-First Century Rate (1.2 percent): 54 years
» Global population in 2100 would reach 24 billion.
– 1963 (2.2): 35 years
» Global population in 2010 would have been 10 billion
instead of nearly 7 billion.
• More than 95 percent of the natural increase is clustered in
developing countries.
Crude Birth Rate:
• Crude Birth Rate (CBR) is the annual number
of live births per 1000 people in a population.
The crude birth rate is the total number of live births in a year for every
1,000 people alive in the society. The global distribution of crude birth
rates parallels that of natural increase rates. Again, the highest crude birth
rates are found in sub-Saharan Africa and the Middle East, whereas the
lowest are in Europe.
CDR/NIR:
• Crude Death Rate: Total # of deaths in a year for
every 1,000 people alive
• Natural Increase Rate: % by which a population
grows per year. Compute by subtracting CDR from
CBR (in percentage)
• CBR is 20, CDR is 5 (per thousand), the NIR is
15 per 1,000, or 1.5%
Mortality Rate
by Country
Crude death rate is the total number of deaths in a year for every 1,000 people alive in the
society. The global pattern of crude death rates varies from those for the other
demographic variables. First, although Europe has the lowest natural increase, crude birth,
and infant mortality rates, it has relatively high crude death rates. Second, the variance
between the highest and lowest crude death rates is much lower than was the case for the
crude birth rates. The concept of the demographic transition helps to explain the
NATURAL INCREASE RATE The world average is currently
about 1.2 percent. The countries with the highest NIRs are
concentrated in Africa and Southwest Asia.
• Zero Population Growth (ZPG): If the CDR is
the same as the CBR. True of most developed
regions (North America, Japan, Europe, etc.).
• Therefore, any increase in population of
these countries is due to what?
• Negative NIR: If the CDR is higher than the
CBR
• Demographic equation: the global difference
between births and deaths
6 Factors that Affect NIR Discussion:
1.
2.
3.
4.
5.
6.
Economic Development:
Education
Gender Empowerment
Healthcare
Cultural Traditions
Public Policy
•
Explain how each of the aforementioned factors might
affect the Natural Increase Rate of a country. Be specific.
6 Factors That Affect NIR?
• Economic Development: affects available healthcare,
employment, nutrition, etc. Generally, increases in
economic development lead to decreases in fertility and
growth rate
• Education: affects fertility, use of contraception (birth
control), etc. Better education leads to lower fertility rates
and lower rates of natural increase
• Gender Empowerment: opportunities available to women.
When women have more economic and political access,
power, and education, fertility drops.
6 Factors That Affect NIR?
• Healthcare: has contradictory effects. Improved
healthcare in less-developed countries has decreased infant
mortality and increased life expectancy, thus contributing
to population growth
• Cultural Traditions: can encourage high fertility rates by
limiting female employment outside the home and
discouraging use of contraception
• Public Policy: governmental programs, like China’s ‘One
Child Policy’ of 1979, provides economic incentives for
people having few children and penalties for those who
have more than one.
Doubling Time:
• The amount of time it takes the world to double it’s
population- in the 1960’s & 70’s the doubling time was
about 35 years
• Major regional differences in rates of growth. NIR exceeds
3% in many parts of Africa, while some of Western Europe
experiences negative population growth.
Total Fertility Rate (TFR):
• Measures the number of births in a country
• TFR is average number of children a woman will have
during her ‘childbearing years’ (approx. ages 15-49) TFR
exceeds six in some African nations.
Infant Mortality Rate (IMR):
• Annual number of infant deaths (children under 1 year of age),
compared with total live births, expressed as a number of deaths per
1,000.
• Exceeds 10% in some nations
• Significant factor limiting population growth
• Babies born in the West expected to live into late Seventies, but only
forties in most Sub-Saharan countries!
Life Expectancy:
• Average length of someone’s life.
• Calculation of LE affected by infant, child, and maternal
mortality rates
• Varies greatly from place to place and within populations
• Factors: violence, disease, poor healthcare, smoking, etc
Life Expectancy at Birth in 2003
Men
Women
US
74
80
Japan
78
85
Nepal
59
58
Kenya
46
46
France
76
83
60 minutes – Bill & Melinda Gates
• http://www.youtube.com/watch?v=2VdM
qmVtnOM