VCE · Geography · Population Dynamicslive from the app
Fertility and mortality
Fertility and mortality are measured by five linked indicators: total fertility rate, crude birth rate, crude death rate, infant mortality rate and life expectancy. The crude rates are per thousand people a year, so they depend on who is in the population: a youthful population has a low crude death rate because few people are old, while an aged population with the longest lives records more deaths per thousand. Natural increase is the gap between crude birth rate and crude death rate, and that gap, not the birth rate alone, decides whether a population grows or shrinks before migration is counted.
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the one idea
why this one carries the topic.
Populations change through three doors: births, deaths and movement. Every projection is a bet on those three.
Five bars for one population type: crude birth rate and crude death rate on a shared per-thousand scale with natural increase shaded as the gap between them, then infant mortality rate, total fertility rate with a replacement marker, and life expectancy. Switching the population type and changing fertility moves the bars and every readout.
what examiners catch — Students write birth rate when they mean total fertility rate, and read a low crude death rate as a sign of good health. In an assessment, name each indicator with its unit (per thousand people, per thousand live births, births per woman, years), and give natural increase as crude birth rate minus crude death rate with its sign.
what you leave with
five things, not forty.
Total fertility rate is births per woman over a lifetime; crude birth rate is births per thousand people a year, so the same fertility gives more births per thousand in a youthful population than in an aged one.
Crude death rate is deaths per thousand people a year; it is often higher in an aged population than in a youthful one, even though people in the aged population live far longer.
Infant mortality rate (infant deaths per thousand live births) and life expectancy measure health directly, and both are worst where fertility is highest.
Natural increase is crude birth rate minus crude death rate, converted from per thousand to a percentage; a negative gap means the population shrinks before migration is counted.
Replacement fertility is about 2.1 births per woman, yet at that level a youthful population still grows and an aged one still shrinks, because age structure keeps working for decades.
High fertility, high infant mortality and short lives cluster in sub-Saharan Africa; low fertility and the longest lives cluster in Europe and East Asia, with most of Asia and Latin America in between.
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this conceptfertility and mortalityFive bars for one population type: crude birth rate and crude death rate on a shared per-thousand scale with natural increase shaded as the gap between them, then infant mortality rate, total fertility rate with a replacement marker, and life expectancy.
sits under itworld population distributionbecause Knowing where people live helps place the youthful, transitional and aged types on the map.
built on itthe demographic transition modelbecause the model plots the two rates
built on itmalthus and the population debatebecause Malthus argued about exactly these rates
built on itmanaging a growing populationbecause Total fertility rate and replacement level are the numbers the picture moves.
the rest of population dynamics
4 more, same treatment.
Each one is its own knowscape in the app — built for how a particular student takes things in, not one explanation handed to everybody.
world population distributionin the appmalthus and the population debatein the appthe demographic transition modelin the appmigration and population pyramidsin the app
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