Questions: Population Dynamics

Question 1

A country has 500,000 births, 300,000 deaths, 50,000 immigrants, and 20,000 emigrants in a year. Its population at the start of the year was 25 million. What is the population at year's end, and what is the rate of natural increase?

• A. 25,230,000; natural increase rate is 0.8%
• B. 25,230,000; natural increase rate is 0.92%
• C. 25,200,000; natural increase rate is 0.8%
• D. 25,170,000; natural increase rate is 0.68%

Answer: (A)

Applying the balancing equation: 25,000,000 + 500,000 - 300,000 + 50,000 - 20,000 = 25,230,000. Natural increase = births - deaths = 200,000. Rate of natural increase = 200,000 / 25,000,000 = 0.008 = 0.8%. Net migration (30,000) adds additional growth beyond natural increase.

Question 2

A country's population growth rate has declined from 2.5% to 1.2% per year. This means the population is shrinking.

• T. True
• F. False

Answer: False

A declining growth rate means the population is growing more slowly, not that it is declining. The population is still increasing — just at a reduced pace. A population only shrinks when the growth rate turns negative, meaning deaths plus emigration exceed births plus immigration.

Question 3

Explain the difference between tempo and quantum in demographic analysis, and why confusing them leads to misinterpretation of trends.

Model answer: Quantum refers to the ultimate level or amount of a demographic event (e.g., how many children a woman will have over her lifetime). Tempo refers to the timing of those events (e.g., the age at which women have children). Confusing them leads to misinterpretation because a shift in timing — such as women delaying childbearing — can temporarily depress period fertility rates even when completed family size remains unchanged. A country may appear to have dangerously low fertility when in fact women are merely having children later, not fewer.

The tempo-quantum distinction, formalized by Norman Ryder and later elaborated by Bongaarts and Feeney, is one of the most important analytical tools in demography. Period measures (calculated for a calendar year) are distorted by tempo shifts; cohort measures (following a real generation) capture quantum more accurately but are only available after a cohort completes its childbearing.