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FrançaisLearning Objectives
- Define and calculate the crude birth rate (CBR), crude death rate (CDR), total fertility rate (TFR), infant mortality rate (IMR), and natural increase rate (NIR).
- Apply the formula NIR = (CBR − CDR) ÷ 10 to compute a country's annual natural growth.
- Use the Rule of 70 to estimate population doubling time at a given growth rate.
- Distinguish between CBR (population-weighted) and TFR (per-woman) and explain when each measure is preferred.
- Identify replacement-level fertility (~2.1) and predict long-term population trajectory from a TFR alone.
Key Concepts
Demographers describe a country's population dynamics with a small number of vital statistics. The AP exam expects you to know each one, calculate when given the data, and explain what differences between countries reveal about development.
A snapshot measure that depends on the population's age structure. Niger's CBR is around 45; Italy's is around 7. The same TFR can produce different CBRs in countries with different age profiles.
Counterintuitive: aging high-income countries (Japan 12, Germany 12) often have higher CDRs than young low-income countries (Niger 8) because older populations die at higher rates.
Per-woman measure independent of age structure. Replacement is ~2.1. Niger's TFR is 6.7; South Korea's is 0.78 (the world's lowest); the US sits at 1.66.
One of the most sensitive development indicators. Sierra Leone's IMR is roughly 80; Iceland's is 1.5. Tracks closely with healthcare access, sanitation, and female education.
Annual percentage growth from births and deaths alone (excluding migration). The world's NIR has fallen from 2.1 percent (1960s peak) to about 0.9 percent today. Some countries (Japan, Italy) are negative.
How many years to double at a constant NIR. NIR 2.0% ⇒ 35 years. NIR 1.0% ⇒ 70 years. NIR 0.5% ⇒ 140 years. Memorize this for the AP exam.
Country Case Studies
Niger
The fastest-growing major country on Earth. NIR of 3.7 percent implies a doubling time of about 19 years. Fertility-driven growth is straining schools, water, and food supply.
Country page →
Japan
One of several countries shrinking from natural decrease alone. Japan loses about 800,000 people per year. The population peaked in 2008 at 128 million and is projected at 88 million by 2065.
Country page →
Sierra Leone
One of the world's highest infant mortality rates. The 2014-16 Ebola epidemic and the legacy of civil war (1991-2002) damaged the healthcare system; recovery is ongoing.
Country page →
South Korea
The lowest TFR ever recorded for a sovereign country. Demographers attribute it to housing costs, child-rearing expense, low female workplace flexibility, and a hyper-competitive education system.
Country page →Discussion Questions
- Japan and Niger both have a CDR of 8-12. Why does Japan's number reflect aging while Niger's reflects something completely different?
- Calculate the NIR for a country with CBR 28 and CDR 8. Then calculate doubling time. What does that imply about its planning horizon for schools and infrastructure?
- South Korea's TFR is 0.78 and falling. If it stayed there, what would happen to the country's population in 50 years (assume no immigration)? In 100 years?
- Why is IMR considered the most sensitive single indicator of national development? What might be a counterexample?
- The world's NIR has fallen by half since the 1960s. Is that mostly because CBR fell, CDR rose, or both? What does the answer imply about the global Demographic Transition?
Classroom Activities
NIR Calculation Drill
The teacher gives students 12 country fact sheets with CBR and CDR. Students calculate NIR and doubling time for each, then rank countries fastest-growing to fastest-shrinking.
Vital Statistics Country Profile
Each student picks one country and pulls all six vital statistics from a current data portal. They write a one-page brief explaining what the country's numbers reveal about its development stage.
Vocabulary
Standards Alignment
Draft alignment — pending educator review. AP HG codes correspond to the official College Board Course and Exam Description (Effective Fall 2020, V.1). Statements below are paraphrased in CountryReports' own voice; refer to the College Board's published CED for verbatim wording.
Suggested Skill
Enduring Understanding
Learning Objective
Essential Knowledge
AP® and Advanced Placement® are registered trademarks of the College Board. The College Board was not involved in the production of this material and does not endorse it. Standards statements above are paraphrased; codes refer back to the official College Board CED, the NCSS C3 Framework, the Common Core State Standards, and other cited frameworks.
AP Practice Questions
- (A) 24 years
- (B) 29 years
- (C) 35 years
- (D) 70 years
- (E) 140 years
Correct: (B). NIR = (32 − 8) ÷ 10 = 2.4%. Doubling time = 70 ÷ 2.4 ≈ 29 years.
Scoring: 1 point for replacement TFR ~2.1; 2 points for two consequences (population decline, aging, dependency-ratio increase, labor shortage); 1 point each for a policy (e.g., parental leave, child subsidies, universal childcare = pro-natalist; immigration, automation, raising retirement age = adaptive).