1. Making sense of the Statistics
Population 102
Making sense of the Statistics

2. The Birth Rate Formula Live Births Pop / 1,000
So, if you have a country with 100,000 births and a pop of 5,000,000 the CBR is 20 (20 for every 1000 of the pop).

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

4. The CDR Formula
Deaths
Pop/1,000
Calculated the same way as CBR

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

6. Formula for NIR (RNI) Birth Rate-Death Rate 10
For example, if a country has a CBR of 27 and a CDR of 12 the NIR equals 1.5 percent…the percent increase in that country’s annual population rise.

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

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

9. Something to Remember about NIR:
Does NOT account for MIGRATION!
A country with a high rate of natural increase can have an unexpectedly low long-term pop prediction if there is a large amount of EMIGRATION.
Conversely, a country with a low rate of natural increase can still grow significantly over time if the IMMIGRATION rate is high.
Data shows that migrant populations are more likely to have higher fertility rates, so population growth may not be from the migrants, but the babies the make once they get there (US).

10. Formula for Doubling Time70
Rate of NIR
Ex: Bolivia has an NIR of 2.1 = doubling time of 33.3 yrs. That’s fast, 10mill people today would grow to 20mill by 2050… but it won’t. Why not? There is a negative net migration in Bolivia. Out-migration to other countries reduces long-term prediction to around 17mill by That’s why NIR is an estimate.

11. Add Migration and you get: The Demographic Equation
Net Migration Rate Formula:
# of Immigrants – # of Emigrants
Pop/1, Pop/1,000
Take this and add it to the birth rate minus the death rate and you will have total population growth per thousand and you have your Demographic Equation like so:

12. Demographic Equation (Birth Rate – Death Rate)+ Net Migration Rate 10
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 migration rate of 3 and we find that the US adds 9 people for every thousand in the population annually. Divide by 10 to find the population growth rate (including immigration) is 0.9 % annually.
= % Rate

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

14. The TFR Formula # of Children Born Women 15-49
Remember, TFR is NOT an annual statistic like NIR. It is more of an estimate, taken as a snapshot of fertility for birth over the prior 30 yrs. Thus TFR and NIR are NOT comparable. They’re two different things. You cannot, for example have a negative TFR. TFR highlights the importance of replacement in the population.
Don’t forget Replacement Rate (2.1) .1 is the error factor

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

16. Making Sense of the Demographic Transition Model

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

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

19. More on the DTM next week