# Impact of Population Change Natural Population Change.

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Impact of Population Change Natural Population Change

Learning outcomes What is natural population change? To define the following measures of fertility and mortality: Crude birth rate Age-specific fertility rate Crude death rate Age-specific mortality rate Infant mortality rate

Population Geography There are more than 6 billion of us on earth The study of population is called demography and involves consideration of birth and deaths (fertility and mortality), the balance of which, in any area, over time, is called natural population change Demography also looks at the causes and impact of migration

Natural Population Change This results from the relationship between births and deaths over time. If there are more births than deaths then the population grows More deaths than births the population falls Natural population change does not involve migration

Crude Birth Rate This is the number of live births per thousand people in an area in any one year 40+ births would be high 10-12 births would be low and representative of a MEDC Calculation:No. of birthsX 1000 Total Population

Generalised Fertility Rate This is sometimes used. This is the number of live births per 1000 women in he fecund ages, 15-44 (sometimes 15-49 used instead)

Total Fertility Rate (TFR) This is the average number of births per woman in a population. Calculation:No. of birthsX1000 No. of women (15-49) For a population to remain stable, there needs to be an average 2:1 children born to each woman Some LEDCS have over 6, some MEDCS have less than 2

Net replacement rate This measures the average number of daughters produced by a woman during their productive lifetimes. A figure of 1 indicates a stationary population Less than 1 the population falls More than 1, it grows

Mortality Mortality is to do with death Crude death rate is the number of deaths per 1000 people in an area per year. Calculation:No. of DeathsX 1000 Total Population

Standardised Mortality rate/ Age specific mortality rates More defined measure looking at population structures Calculation:(e.g.) No. of deaths (30-39yrs)X1000 Total no. of 30-39yrs

Infant mortality rate (IMR) Measures the number of babies and infants per 1000 live births who die before their first birthday in an area in a year Some LEDCS the IMR is 120 per 1000 and accounts for 30% of the deaths

Life expectancy Measures the number of years on average to be lived, usually from birth Modern life expectancy can range from age 30-80

Recap You should be able to define the following: Crude birth rate Total fertility rate Net replacement rate Crude death rate Infant mortality rate Standardised mortality rate Life expectancy

Now: Use The Impact of Population Change Page 4 to copy out definitions Homework: learn meanings for short test

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