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Key population terms

Population density – relates population to area, (average) the total population in a country or region divided by its area (people/km2).

Crude birth rate – the number of births per 1000 people (CBR).

Crude death rate – the number of deaths per 1000 people (CDR).

Natural increase – The difference between the CBR & the CDR usually expressed as a % per year. Natural increase (%) = CBR – CDR.


Demographic transition – describes what has happened to birth & death rates in today’s MEDCs since 1800.

Migration – controls the shape of population pyramids, at a natural scale, birth & death rates are most important, migration is important in smaller areas (cities/ regions).

Life expectancy – how long people in certain countries are expected to live.

Age dependency – percentage of population that depend on economic support (e.g. pension for the elderly, school for the young).

Replacement level – the rate that is needed to replace both parents.

Family planning – birth rates have fallen where children have been immunised & where mothers have received some education.

Population pyramids – age & sex structure of a population can be shown in this type of graph, factors control the shape, birth & death rates & migration.