Population 102Population 102

Making sense of the StatisticsMaking sense of the Statistics

The Birth Rate FormulaThe Birth Rate Formula

Live BirthsLive Births

Pop / 1,000Pop / 1,000

So, if you have a country with 100,000 So, if you have a country with 100,000 births and a pop of 5,000,000 the CBR is births and a pop of 5,000,000 the CBR is 20 (20 for every 1000 of the pop). 20 (20 for every 1000 of the pop).

What does CBR tell you?What does CBR tell you?

High birth rates (18-50) are found in High birth rates (18-50) are found in mostly rural agricultural LDCs and those mostly rural agricultural LDCs and those with low rates (8-17), are more likely found with low rates (8-17), are more likely found in urbanized, industrial and service-based in urbanized, industrial and service-based economies. However, without knowing economies. However, without knowing whats going on with mortality its hard to whats going on with mortality its hard to know whether the pop is growing and how know whether the pop is growing and how quickly if it is. quickly if it is.

The CDR FormulaThe CDR Formula

DeathsDeaths

Pop/1,000Pop/1,000

Calculated the same way as CBRCalculated the same way as CBR

What does the Death Rate tell you?What does the Death Rate tell you?

Well, not much today. High death rates Well, not much today. High death rates usually indicate a country experiencing usually indicate a country experiencing war, disease, or famine. Historically, war, disease, or famine. Historically, higher CDR (20-50) were recorded in higher CDR (20-50) were recorded in LDCs due to a combination of poverty, LDCs due to a combination of poverty, poor nutrition, epidemics, lack of medical poor nutrition, epidemics, lack of medical care resulted in low care resulted in low life expectancylife expectancy. . However, conditions have improved due to However, conditions have improved due to the the Green RevolutionGreen Revolution

Formula for NIR (RNI)Formula for NIR (RNI)

Birth Rate-Death RateBirth Rate-Death Rate

1010

For example, if a country has a CBR of 27 For example, if a country has a CBR of 27 and a CDR of 12 the NIR equals 1.5 and a CDR of 12 the NIR equals 1.5 percent…the percent increase in that percent…the percent increase in that country’s country’s annual population rise. annual population rise.

Negative NIR: Is it Possible?Negative NIR: Is it Possible?

Yes, in a couple of situations. Yes, in a couple of situations. Mathematically, the death rate can be Mathematically, the death rate can be larger than the birth rate. When the NIR is larger than the birth rate. When the NIR is negative it means the pop has shrunk negative it means the pop has shrunk during the year the data was collected. during the year the data was collected. One current example is One current example is SwazilandSwaziland (Africa) (Africa) where the AIDS epidemic has decimated where the AIDS epidemic has decimated the population NIR: -0.1%the population NIR: -0.1%

There are other explanations: There are other explanations:

Negative NIR cont.Negative NIR cont. Another explanation are MDCs that are Another explanation are MDCs that are

highly urbanized and the roles of women highly urbanized and the roles of women in the country have become such that in the country have become such that traditional roles of mother and homemaker traditional roles of mother and homemaker have deteriorated significantly…increasing have deteriorated significantly…increasing gender equality. Focus on career, political gender equality. Focus on career, political activity, social networks, etc women are activity, social networks, etc women are less likely to have kids (reduced less likely to have kids (reduced fecundityfecundity) ) phenomena called phenomena called double-income no-kid double-income no-kid (DINK) households(DINK) households, and , and single parent-single parent-single child homessingle child homes. Higher divorce rates . Higher divorce rates are another sign. are another sign. GermanyGermany is a prime is a prime example NIR: -0.1 to -0.2example NIR: -0.1 to -0.2

Something to Remember about Something to Remember about NIR:NIR:

Does NOT account for MIGRATION!Does NOT account for MIGRATION! A country with a high rate of natural increase A country with a high rate of natural increase

can have an unexpectedly low long-term pop can have an unexpectedly low long-term pop prediction if there is a large amount of prediction if there is a large amount of EMIGRATIONEMIGRATION..

Conversely, a country with a low rate of natural Conversely, a country with a low rate of natural increase can still grow significantly over time if increase can still grow significantly over time if the the IMMIGRATIONIMMIGRATION rate is high. rate is high.

Data shows that migrant populations are Data shows that migrant populations are moremore likely to have higher fertility rates, so population likely to have higher fertility rates, so population growth may not be from the migrants, but the growth may not be from the migrants, but the babies the make once they get there (US). babies the make once they get there (US).

Formula for Doubling TimeFormula for Doubling Time

7070

Rate of NIRRate of NIR

Ex: Ex: BoliviaBolivia has an NIR of 2.1 = doubling time of has an NIR of 2.1 = doubling time of 33.3 yrs. That’s fast, 10mill people today would 33.3 yrs. That’s fast, 10mill people today would grow to 20mill by 2050… but it won’t. Why not? grow to 20mill by 2050… but it won’t. Why not? There is a negative net migration in Bolivia. Out-There is a negative net migration in Bolivia. Out-migration to other countries reduces long-term migration to other countries reduces long-term prediction to around 17mill by 2050. That’s why prediction to around 17mill by 2050. That’s why NIR is an estimate. NIR is an estimate.

Add Migration and you get: Add Migration and you get: The Demographic EquationThe Demographic Equation

Net Migration RateNet Migration Rate Formula: Formula:

# of Immigrants # of Immigrants – – # of Emigrants # of Emigrants

Pop/1,000 Pop/1,000Pop/1,000 Pop/1,000 Take this and add it to the birth rate minus Take this and add it to the birth rate minus

the death rate and you will have total the death rate and you will have total population growth per thousand and you population growth per thousand and you have your have your Demographic EquationDemographic Equation like so: like so:

Demographic EquationDemographic Equation

(Birth Rate – Death Rate)+ Net Migration Rate (Birth Rate – Death Rate)+ Net Migration Rate

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Take the US as an example: the US has a birth rate of Take the US as an example: the US has a birth rate of 14 and a death rate of 8. Add the product to a net 14 and a death rate of 8. Add the product to a net migration rate of 3 and we find that the US adds 9 migration rate of 3 and we find that the US adds 9 people for every thousand in the population annually. people for every thousand in the population annually. Divide by 10 to find the population growth rate Divide by 10 to find the population growth rate (including immigration) is 0.9 % annually. (including immigration) is 0.9 % annually.

= % Rate

Net Migration Rates can be Net Migration Rates can be Negative:Negative:

Guyana, in S. America has net emigration Guyana, in S. America has net emigration to such a degree that population is to such a degree that population is expected to fall over the long-term. Their expected to fall over the long-term. Their birth rate is 21 and death rate is 9. Adding birth rate is 21 and death rate is 9. Adding to the net migration rate of -10 (that is by to the net migration rate of -10 (that is by subtracting 10), we find that the population subtracting 10), we find that the population growth is only 1% per thousand or 0.1% growth is only 1% per thousand or 0.1% In the future that number is expected to be In the future that number is expected to be -0.1%-0.1%

The TFR FormulaThe TFR Formula

# of Children Born# of Children Born Women 15-49Women 15-49 Remember, TFR is NOT an annual statistic like Remember, TFR is NOT an annual statistic like

NIR. It is more of an estimate, taken as a NIR. It is more of an estimate, taken as a snapshot of fertility for birth over the prior 30 yrs. snapshot of fertility for birth over the prior 30 yrs. Thus TFR and NIR are NOT comparable. Thus TFR and NIR are NOT comparable. They’re two different things. You cannot, for They’re two different things. You cannot, for example have a negative TFR. TFR highlights example have a negative TFR. TFR highlights the importance of replacement in the population.the importance of replacement in the population.

Don’t forget Don’t forget Replacement RateReplacement Rate (2.1) .1 is the (2.1) .1 is the error factorerror factor

Keep getting TFR and NIR Keep getting TFR and NIR confused?confused?

Remember this car analogy to remember Remember this car analogy to remember the difference: When a country’s TFR the difference: When a country’s TFR drops to 2.1 (replacement rate) you’ve hit drops to 2.1 (replacement rate) you’ve hit the breaks on the car and the speed the breaks on the car and the speed population growth slows down. Its not til population growth slows down. Its not til the NIR hits 0 that the car comes to a the NIR hits 0 that the car comes to a complete stop. The NIR can go negative complete stop. The NIR can go negative and the car (pop.) rolls backward = and the car (pop.) rolls backward = shrinking pop. shrinking pop.

Making Sense of the Making Sense of the Demographic Transition ModelDemographic Transition Model

About the Model:About the Model: The DTM has a number of uses. You should think of it The DTM has a number of uses. You should think of it

as a central unifying concept in your understanding of as a central unifying concept in your understanding of the AP Human Geography course. Not only is it a the AP Human Geography course. Not only is it a theory of how pop changes over time, but it also theory of how pop changes over time, but it also provides important insights into issues of migration, provides important insights into issues of migration, fertility, economic development, industrialization, fertility, economic development, industrialization, urbanization, labor, politics, and the roles of women. urbanization, labor, politics, and the roles of women. By placing a country on the model, you are defining By placing a country on the model, you are defining the the population dynamicspopulation dynamics and and economic contexteconomic context of the of the country. Knowing where a country falls on the model country. Knowing where a country falls on the model lets you know what kind of economy it has, migration lets you know what kind of economy it has, migration patterns, etc… this “picture” of a country’s population patterns, etc… this “picture” of a country’s population can tell you much about its quality of life. can tell you much about its quality of life. REMEMBER, the model is a theory and not perfect; it REMEMBER, the model is a theory and not perfect; it provides estimates and averages. provides estimates and averages.

The Crystal BallThe Crystal Ball The model also has a predictive capability. The model also has a predictive capability.

If a country falls within stage 2 of the If a country falls within stage 2 of the transition, we can use this model to predict transition, we can use this model to predict how its population will change over time how its population will change over time and speculate as to how much it can grow and speculate as to how much it can grow in size. Likewise, you can look at the in size. Likewise, you can look at the whole world, which falls into early stage 3. whole world, which falls into early stage 3. Knowing this, we can estimate a Knowing this, we can estimate a population projectionpopulation projection that the planet’s that the planet’s population potentialpopulation potential has only reached 2/3 has only reached 2/3 of its potential. of its potential.

More on the DTM next weekMore on the DTM next week