Populations and how they change.
Answer five questions about Demography and get instant feedback.
What can increase through in-migration even with zero births?
Even if no babies are born, a town can still grow when more people move in than leave, which is why migration can quickly reshape schools, jobs, and housing.
What aspect of a population can make two equally sized populations need very different numbers of schools?
Two places with the same total population can need wildly different school budgets if one has a big "youth bulge" and the other is mostly retirees.
This image question appears in the interactive quiz.
A population pyramid can reveal aging, rapid growth, or past demographic shocks.
Expected number of children per woman under current age-specific birth rates
Because it is built from age-specific rates, the total fertility rate can change even if the number of births stays flat, just because the population's age structure shifts.
In a closed population, migration is assumed to be ...
Treating migration as absent lets you isolate natural increase, so $\Delta N = B - D$ and any mismatch with observed change becomes a clean estimate of net migration.
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