Population Growth/Decline: Fertility, Mortality and Migration – Demographic Shifts and Social Change (SOC)

00:01 Now, I made the same concepts here on population pyramids.

00:03 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.

00:12 It shows the distribution of the population by both age and gender which forms the shape of the pyramid when the population is growing.

00:19 At the bottom, we have the youngsters.

00:22 And at the top, we have what it says age we’re going to have our elderly folk.

00:26 And so this diagram, it is then further split in half and we have our males and our females.

00:31 And you could see at the base of this pyramid, if it’s a wide base that means we have a lot of growth.

00:36 And if it’s a narrow peak that means we don’t have a lot of deaths.

00:39 Okay, so this would be a growing population more births than deaths, okay.

00:45 There's different types of population pyramids that can be applied to the different stages that we just went over.

00:52 You’d have an expanding population pyramid, and this would be stage 1.

00:56 Or we have a quite a few births happening.

00:58 But then, this will continue as we have a lot of births and we start to see a stabilization in the amount of deaths.

01:07 At this point, we still have a lot of births but then we’re starting to see more increased death as well.

01:15 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.

01:27 And so, this would be a contracting population.

01:30 So we go from expanding to stationary to contracting.

01:34 Now, let’s take a look at Fertility, Migration and Mortality.

01:39 And these are three factors which will shape our population dynamics.

01:43 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.

01:51 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.

01:57 And it’s really hard to also relate because of the differences and population size globally speaking.

02:03 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.

02:15 So you go over a simple straightforward period of a year.

02:18 and you look at it per a thousand people.

02:21 And these rates can modulate over a lifespan. And so we agree to use this for on a age-specific values.

02:29 We kind of further stratified based on age.

02:31 Total fertility is the average number of children that would be born to woman over her reproductive lifetime. And you can calculate this number.

02:41 And that’s different then say, Crude birth rate, which looks at births per a thousand people irrespective of the age composition.

02:48 So, if they look at this number and you have something less than two, that would mean you have a decline.

02:56 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.

03:05 And if there only reproducing and having one child, they’re at some point going to die.

03:10 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.

03:19 Okay? Now, if they are two, and they have two, then they’re equal it’s balanced.

03:26 And anything above two represents an increase in the population. So you see growth.

03:30 So based on this figure you see decline in growth based on the number of children that you have.

03:35 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.

03:47 And therefore, that we know it’s an increase in population.

03:50 So here’s the total fertility rate for certain countries in 2010.

03:55 This is based on data from the UN.

03:58 And you can see those that are above two and those are below two.

04:02 So those that are over two would show an increase in population.

04:05 And countries like the States just to make it.

04:08 And we have other countries, we are starting to see a decrease in their overall population.

04:14 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.

04:22 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.

04:31 So we say of the destination country or our home resident country.

04:37 So if there is economic instability, they’re going to want to leave.

04:42 If the things were great, that’s where people don’t want to go.

04:45 And we also understand too that better quality of life and healthcare will determine whether or not people want to go.

04:51 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.

05:01 Now, internal migration refers to the movement of individual within their own country.

05:06 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.

05:15 And that’s different then leaving your actual country.

05:18 Now, we can use this to figure out something called Net migration.

05:22 Which is calculated by subtracting immigration from emigration.

05:25 So for talking about internal migration that’s different because you’re still staying within a country.

05:30 As supposed to Net migration as you actually leaving.

05:33 People leaving, people coming.