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A growing population. Global Geography 12. Measuring Population Growth.
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A growing population Global Geography 12
Measuring Population Growth A population pyramid, also called an age structure diagram, is a graphical illustration that shows the distribution of various age groups in a population (typically that of a country or region of the world), which forms the shape of a pyramid when the population is growing. Typically, demographers categorize any population they examine into male and female components by age division called cohorts.
Measuring Growth Continued • Cohorts -a group of subjects with a common defining characteristic — typically age group • When measuring population composition of a specified country, the most common cohorts are in five-year intervals which is commonly used in the age-sex structure.
How to measure growth Population Growth Rate = (Birth Rate + Immigration) – (Death Rate + Emigration) Rate of Natural Increase (RNI) = Birth Rate – Death Rate/10 Doubling Time = Doubling Time = 70/RNI
Population Pyramids • In a population pyramid, bars indicating the male portion of the population is extended to the left of the vertical axis and the female portion extend to the right. • The bars for all the age cohorts are stacked one on top of the other, starting with the bars from the youngest cohort at the bottom.
Types of Population Pyramids While all countries' population pyramids differ, there are four general types have been identified by the fertility and mortality rates of a specific country.
Expansive pyramid - A population pyramid showing a broad base, indicating a high proportion of children, a rapid rate of population growth, and a low proportion of older people. This wide base indicates a large number of children. A steady upwards narrowing shows that more people die at each higher age band. This type of pyramid indicates a population in which there is a high birth rate, a high death rate and a short life expectancy. This is the typical pattern for less economically developed countries, due to little access to and incentive to use birth control, negative environmental factors (for example, lack of clean water) and poor access to health care.
Constrictive pyramid A population pyramid showing lower numbers or percentages of younger people. The country will have a greying population which means that people are generally older, as the country has long life expectancy, a low death rate, but also a low birth rate. This pyramid has been occurring more frequently, especially when immigrants are factored out, and is often a typical pattern for a very developed country, a high over-all education and easy access and incentive to use birth control, good health care and few or no negative environmental factors.
Stationary pyramid A population pyramid typical of countries with low fertility and low mortality, very similar to a constrictive pyramid.
Stable pyramid A population pyramid showing an unchanging pattern of fertility and mortality.
Using Population Pyramids Population pyramids can be used to observe; Rate if natural increase (RNI) Birth Rates and Death Rates Dependency Ratio
What is dependency ratio? Dependency Ratio is an age-population ratio of those typically not in the labour force (the dependent part) and those typically in the labour force (the productive part). It is used to measure the pressure on productive population
Dependency Ratio • Population pyramids can be very useful in determining the dependency ratio of a country. • The dependency ratio of a population is based on the assumption that most members of a certain age groups (very young or very old) do not work.
Possible Issues? • A high dependency ratio can cause serious problems for a country. As the largest proportion of a government's expenditure is on health, social security & education which are most used by old and young population. • Also the increasing expenditure on pension becomes a problem too.
Measuring Dependency Ratio • Dependency Ratio = (% under 15) + (% over 65) x 100 % Between 15 - 65
For Example . . . • A worked example should make this clearer. Pakistan, which is a developing country, has 41% of its population less than 15, and 4% over 65. This makes 55% (100 - (41+4)) between the ages of 15 and 64. Dependency Ratio = (41) + (4) x 100 55 = 45 x 100 55 = 81.8
What’s the difference? • Emigration – Occurs when people leave their home country to pursue a new life in a new country. • Immigration – Occurs when people enter a new country from their original home country.
Factors contributing to emigration Factors contributing to emigration include; The search for a better standard of living. Freedom (Political or Economic) Lack of employment, or other working opportunities. Shortage of farmland, no arable land sources. Restrictions on religious practices.
Factors contributing to immigration • Factors include; Higher standard of living Educational opportunities Employment opportunities Freedom of expression (religion or otherwise) Political Reasons
Understanding migration • Both emigration and immigration contribute to factors called “push and pull factors” • These terms help us understand the focus causing migration. • Assist us in understanding the increases and decreases in population and how these factors differ from country to country.
Refugees Refugees – Those who flee their country because of reasons such as; political unrest, disease and famine. Refugees are pushed from their homes and seek refuge elsewhere for safety and security.
disadvantages The disadvantage of being a refugee instead of am immigrant is . . . Often times refugees are not accepted as immigrants to the country in which they flee.
Immigrant vs. refugee status Upon resolution of their homeland’s issues, refugees are required to return. Although immigrants leave their countries for similar reasons, there are legal documents involved. In a refugee situation, there rarely are.
The end result Although many countries accept refugees from a purely humanitarian standpoint, refugees are still required to return to their nations when issues such as famine, disease and war have been resolved.
