# Demography PP

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```					Demography

Demography is the study of populations. It helps answer
questions such as:

 Why are more schools closing than opening?
 Why will you likely have to work more years than your
parents before retiring?
 Why are old rock-and-roll groups, such as the Rolling
Stones, still so popular?
…?
How do we compare countries that have populations of
different sizes?

We use RATES, not NUMBERS!
Look at the number of births for these
three countries:

 Canada: 330,000 babies born in 2003
 Russia: 1,458,000 babies born in 2003
 Togo: 191,000 babies born in 2003
To calculate each country’s birth rate,
divide the number of births in one year by
the population, and multiply the result by
1000.
Math!

births
1000   birthrate
population
So...birth rate...

• Canada (330 000 / 32 207 000)  1000 = 10
• Russia (1 458 000 / 144 526 000)  1000 = 10
• Togo (191 000 / 5 429 000)  1000 = 35
In a similar fashion, rates can be calculated for:

•number of deaths
•number of immigrants
•number of emigrants                 MORE
Math?
deaths
1000  deathrate
population

immigrants
1000  immigrationrate
population
Rates can also be combined in the following
manner:

• natural increase rate = birth rate –
death rate
• net migration rate = immigration rate –       Oh
emigration rate                              come
on!

 births             deaths           
           1000            1000 
population         population        
Population Growth Rate

A country’s population growth rate
= natural increase rate + net

The thesis is the big idea; it’s the key to any
persuasive piece of writing.

It's the point you want to prove.

It's the focus of the whole thing.

Everything you do in the piece should grow from
your thesis--that's how important it is.
So, here’s the statement:

The rate at which a country’s population grows or
declines has an enormous influence on people’s lives.

Come up with a thesis statement that agrees or
disagrees with the statement.
Comparing Population Growth Rates

These population growth rates may not seem
very different:

• Russia – 0.4%
• Togo - 2.4%

But we need to consider the impact of
“compounding.”
The Power of Compounding
offer you two choices. For 30 days, you can receive one
of the following:

»Fig. A \$1000 + \$1000 + \$1000 + \$1000 …   »Fig. B 1 cent + 2 cents + 4 cents + 8 cents …

Which one would you chose: Fig. A or Fig. B?
If you selected Fig. B, you would have a lot more money
for your education. Why? Because growth occurs on top
of the growth that has already taken place.

»Fig. A \$30 000             »Fig. B \$10 737 418.23
Here is the impact of compounding on the populations of
Canada, Russia, and Togo for the next 100 years.
Doubling Time
Doubling time is the time it takes a
population to double at its current growth
rate.
That’s it,
• You could calculate doubling time with       I’m
fancy mathematics…                         leaving!
…

• Or, you could estimate the time by…
…using the Rule of 70, which
states that doubling time
is equal to 70 divided by the
population growth rate.

rate is 0.8%.                     stay!

time is approximately 87
years (70/0.8).
• Canada’s doubling time is 87 years.
• Togo’s doubling time is 30 years (70/2.4).

Which country can more easily deal with its population
growth?

VS.
Population Pyramids

It is easier and faster to
understand population
structure if the data are
graphed.

Two bar graphs are
constructed.

The first one looks like this.
The second bar
graph looks like
this.
Combine the two sets of bar graphs to create a
population pyramid that shows the age/gender
breakdown of a country’s population.
The dependency load is the part of the population that
needs to be supported. It is made up of two components:
the 0–14 age groups and the 65+ age groups.
What has happened to the dependency load between
1956 and 2004?
What is the significance of this change?
Stages of Population Change

Populations within countries change over time in a
predictable manner.

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 views: 4 posted: 4/6/2012 language: English pages: 26