Now, I made the same concepts here
on population pyramids.
And this is one way to actually look at, what
is the distribution of your current population?
It’s splitting it by age and gender.
It shows the distribution of
the population by both age and gender
which forms the shape of the pyramid
when the population is growing.
At the bottom, we have the youngsters.
And at the top, we have what it says
age we’re going to have our elderly folk.
And so this diagram, it is then further split
in half and we have our males and our females.
And you could see at the base of
this pyramid, if it’s a wide base
that means we have a lot of growth.
And if it’s a narrow peak that means
we don’t have a lot of deaths.
Okay, so this would be a growing
population more births than deaths, okay.
There's different types of population
pyramids that can be applied
to the different stages
that we just went over.
You’d have an expanding population pyramid,
and this would be stage 1.
Or we have a quite a few births happening.
But then, this will continue
as we have a lot of births
and we start to see a stabilization
in the amount of deaths.
At this point, we still have a lot of births
but then we’re starting to see
more increased death as well.
At this point, we are starting to see
actually a shrinking population because
the base of this pyramid is
getting smaller a lot less birth
and the top we’re starting
to see a wider more death.
And so, this would be a contracting population.
So we go from expanding to
stationary to contracting.
Now, let’s take a look at
Fertility, Migration and Mortality.
And these are three factors which
will shape our population dynamics.
So we’re going to each.
So for fertility and mortality rates
are typically measured over a period
of about a year for a thousand people.
And now, we could do it so you’re
trying to get the whole population
but it becomes kind of unmanageable.
Do you know what this large numbers in it.
And it’s really hard to also relate because
of the differences and population size
Now, the reason you want some
of this values is to figure out,
Well, internally, how are we changing
in terms of fertility rates?
But then, maybe how are we across
cities, provinces, countries
and these allows you to compare.
So you go over a simple
straightforward period of a year.
and you look at it per a thousand people.
And these rates can modulate
over a lifespan. And so we agree
to use this for on a age-specific values.
We kind of further stratified based on age.
Total fertility is the average number
of children that would be born to woman
over her reproductive lifetime.
And you can calculate this number.
And that’s different then say, Crude birth rate,
which looks at births per a thousand people
irrespective of the age composition.
So, if they look at this number
and you have something less than two,
that would mean you have a decline.
Because you have to time mortality rate.
If you have two people,
a mother and a father, a male or female,
that represents two in a population.
And if there only reproducing and having
one child, they’re at some point going to die.
And so, they were two and they died, and
they’re only bringing one in to replace them
the numbers are going to
go down over a population.
Okay? Now, if they are two, and they have
two, then they’re equal it’s balanced.
And anything above two represents an increase
in the population. So you see growth.
So based on this figure you see decline in growth
based on the number of children that you have.
So, currently I believe the fertility rate
in the US is 2,1 children. So we’re saying,
How do you have a 0,1 child?
It’s more a round in terms of the numbers.
And we know that we’re over two.
And therefore, that we know
it’s an increase in population.
So here’s the total fertility rate
for certain countries in 2010.
This is based on data from the UN.
And you can see those that are
above two and those are below two.
So those that are over two
would show an increase in population.
And countries like the States just to make it.
And we have other countries,
we are starting to see a decrease
in their overall population.
Okay, so let’s also take a look
at some of factors that impact
another issue that we are going to look at
that’s migration or movement of people.
So factors that drive migration can include
economic and political stability or instability
of where they’re coming from
or where they’re trying to go to.
So we say of the destination country
or our home resident country.
So if there is economic instability,
they’re going to want to leave.
If the things were great,
that’s where people don’t want to go.
And we also understand too that
better quality of life and healthcare
will determine whether
or not people want to go.
Or if you have a country where
healthcare is essentially not existent,
there's no doctors, there is
no hospitals that’s going to be a driver
for wanting to push people away
especially if they’re on a situation
where they need actual healthcare.
Now, internal migration refers to the movement
of individual within their own country.
So you might have migrants
that move from the east to the west
within a certain country or region
because of employment or access to resources.
And that’s different then
leaving your actual country.
Now, we can use this to figure out
something called Net migration.
Which is calculated by subtracting
immigration from emigration.
So for talking about internal
migration that’s different
because you’re still
staying within a country.
As supposed to Net migration
as you actually leaving.
People leaving, people coming.