Demography: population momentum: practice question

A PSM question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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PSM · Demography: population momentum

Sample item

A country's total fertility rate has fallen to the replacement level, yet its population is expected to keep rising for another 30 to 40 years. What best explains this?

AThe crude death rate will rise sharply and distort the figuresBLife expectancy will fall and increase the dependency ratioCReplacement level fertility is not enough to stop growth in any settingDA large cohort of young people is entering the reproductive ages

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. A large cohort of young people is entering the reproductive ages

Population momentum is the continued growth after fertility reaches replacement, caused by a young age structure in which many people are entering or in the reproductive years. Growth only stops once these large cohorts have passed through.

Option by option

A. The crude death rate will rise sharply and distort the figures
A rising death rate would slow growth, not explain continued increase.
B. Life expectancy will fall and increase the dependency ratio
A falling life expectancy would reduce growth and is not the explanation.
C. Replacement level fertility is not enough to stop growth in any setting
A fertility rate at replacement level does lead to a stationary population in the long run.
D. A large cohort of young people is entering the reproductive ages (correct)
Correct. A young age structure produces many births even at replacement fertility.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this PSM question

What is the answer to this PSM question?

The best answer is D, A large cohort of young people is entering the reproductive ages. Population momentum is the continued growth after fertility reaches replacement, caused by a young age structure in which many people are entering or in the reproductive years.

Why is "The crude death rate will rise sharply and distort the figures" not the answer?

A rising death rate would slow growth, not explain continued increase.

Why is "Life expectancy will fall and increase the dependency ratio" not the answer?

A falling life expectancy would reduce growth and is not the explanation.

Why is "Replacement level fertility is not enough to stop growth in any setti…" not the answer?

A fertility rate at replacement level does lead to a stationary population in the long run.

What concept does this question test?

It tests Demography: population momentum in PSM. Growth only stops once these large cohorts have passed through.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Demography: population momentum?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.