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# Measuring Population Change.  2 aspects of population that demographers want to know more about: size and rate of change  Size = actual number of people.

## Presentation on theme: "Measuring Population Change.  2 aspects of population that demographers want to know more about: size and rate of change  Size = actual number of people."— Presentation transcript:

Measuring Population Change

 2 aspects of population that demographers want to know more about: size and rate of change  Size = actual number of people in a population at a given time in history  Rate of change = how a population has changed over a period of time. Often referred to as population growth (pop. rarely shrinks )

Absolute vs. Relative  Absolute population change- actual number of people that a population has increased or decreased by over a period of time  Relative population change (or population growth rate) – average annual percentage change over this same time period

Relative population calculation  Find the absolute change (change from one time period to another)  Divide the absolute change by the original population and multiply by 100 (gives a % of change)  Relative change stated as an annual rate so % must be divided by the number of years over which the population change took place

Example 1. Country A- population 1970 = 21 089 000 population 1990 = 27 297 000 population 1990 = 27 297 000 2. Absolute change = 27 297 000 – 21 089 000 = 6 208 000 = 6 208 000 3. % of change = absolute change / 1970 pop. * 100 6 208 000 / 21 089 000 * 100 = 29.4 6 208 000 / 21 089 000 * 100 = 29.4 4. Annual growth rate = % of change / # of years 29.4 / 20 years = 1.47 29.4 / 20 years = 1.47

Calculate the relative population change for the following countries… Country A- 1970 population = 90 840 000 1990 population = 150 400 000 1990 population = 150 400 000 Country B – 1970 population = 4 703 000 1990 population = 5 020 000 1990 population = 5 020 000

Factors affecting population change 4 factors: –Number of people born –Number of people who die –Number of people who move into the country –Number of people who leave the country Because these stats are so important they are called vital statistics

Birth and Death Rates Rates of fertility (birth) and mortality (death) are recorded as the number of birth or deaths per 1000 people per year Eg. Canada’s birth rate in 1998 was 12/ 1000 Because these rates are calculated on the basis of the entire population, regardless or age or sex, they are termed crude rates

Rate of natural increase  Birth rate (BR) – death rate (DR) = annual rate of population growth OR the rate of natural increase (RNI)  BR/ 1000 – DR/ 10000 = RNI / 1000  Population growth usually expressed as percentage therefore have to convert

Example In 1998 Canada’s BR/ 1000 = 12 DR/ 1000 = 7 DR/ 1000 = 7 BR/ 1000 – DR/ 1000 = RNI/ 1000 12- 7 = 5 12- 7 = 5 RNI/ 1000 = 5/ 1000 To change to a % : Convert denominator to 100 = 0.5/ 100 = 0.5% per year = 0.5% per year

Calculate the RNI in % for the following…  Algeria – BR = 31, DR = 7  Niger- BR = 53, DR= 19  Japan- BR = 10, DR = 7  Dominican Republic- BR= 27, DR= 6  Afghanistan- BR= 43, DR= 18  Norway- BR= 14, DR= 10  South Africa- BR= 27, DR= 11  Colombia- BR= 27, DR= 6

Factors Influencing Birth Rates  Number of women in pop.  Age of women in pop.  Economic status and education levels of women  Culture and religious beliefs  Medical conditions and general level of health care  Government population policies

Factors influencing death rates  Availability of medical services and costs associated with them  Contraction of preventable diseases  Education  Availability of clean water and food  Level of economic development  Environmental disasters  Countries fertility rate

Fertility rates  Closely related to birth rates  Total fertility rates (TFR)- average number of children a women would have in her lifetime if the annual birth rates remained constant  Tends to be higher in LDC’s

Replacement levels  The amount of children each woman needs to have to maintain the countries level of population  Eg. 2.1 children / female in a MDC and about 2.5 children / female in a LDC

Migration  People moving in and out of a country  2 types :  Immigration- people moving to a country  Emigration- people moving out of a country

Push and Pull Forces  Conditions that help us understand the forces that cause migration  Push forces- conditions in home country that make a person want to leave (ex. Lack of jobs, poor education system)  Pull forces- advantageous conditions in receiving country that draw a person there (ex. Good social programs, friends and family)

Refugees  Due to worsening political and economic situations in many areas of the world means that push factors out weigh the pull factors  Refugees are people escaping war, life-threatening discrimination, famine, floods, and other natural disasters

 They must enter the new country without permission therefore they do not have any legal standing  Some governments welcome refugees as new citizens on humanitarian grounds. Other refugees will have to return to their homeland once conditions there have improved

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