Presentation on theme: "Population Pyramids We are working through pages 175 to 178."— Presentation transcript:
Population Pyramids We are working through pages 175 to 178
An Introduction to Population Pyramids The composition of any population, that is, the ages and sex of the members of that population, is of particular interest to demographers. cohorts.Typically demographers categorize any population into its male and female components by age divisions called cohorts. The most common cohorts are divided into 5 year intervals. age-sex structureThis information can be presented using an age-sex structure called a population pyramid, as the information pertaining to countries resemble a triangular or pyramidal shape. the male portion to the left female portion extend to the right.In a population pyramid, bars indicating the male portion of the population extend to the left of a vertical axis, while bars indicating the female portion extend to the right. The bars are stackedThe bars are stacked on top of each other, starting with the bars for the youngest cohort at the bottom.
expansivestationaryIn modern times a population pyramid tends to be classified as either expansive or stationary. This indicates a high birth rate and an expanding population.Expansive Age-sex Structure: A population pyramid with a wide base and narrower top. This indicates a high birth rate and an expanding population. Population pyramids of LDCs (Less Developed Countries) typically have a wide base and a narrow top. This represents a high birth rate and high death rate. Stationary age-sex structures are characteristic of countries where both the death rate and birth rate are very low.Stationary Age-sex Structure: A population pyramid that indicates no or very little population growth. Stationary age-sex structures are characteristic of countries where both the death rate and birth rate are very low. The pyramid is characterized by relatively straight sides. Population pyramids of MDCs (More Developed Countries) typically have a roughly equal distribution of population throughout the age groups. The top obviously gets narrower as a result of deaths.
Different Ages – Different Roles Demographers identify three important stages:At each stage of our lives, we play different roles. Demographers identify three important stages: Children (up to age 15) Working adults (ages 16 to 64) Other adults (65 and over) The assumption is that children and older adults are not working and must be supported by the working population. dependency ratio.The proportion of the population that must be supported is called the dependency ratio. We can calculate the dependency ratio by adding together the percentage of those under fifteen and those over sixty-four, and then dividing this sum by the percentage of those in the potential labour force (ages 15 to 64). For example, (see page 175 in the text) using the population pyramid of Canada in 1961, the dependency ratio for each member of the potential work force, plus himself or herself, supports 0.73% or you could say that there are 73 dependants for every 100 people in the potential labour force. Percent under 15 + percent over 64 = 33.8 + 8.4 Percent 15-64 57.8 Percent 15-64 57.8 = 0.73%
A high dependency load, of either children or older people, tends to put a great deal of pressure on the society to provide education, housing, health care, old-age homes, and other needs. Canada today has a dependency load of 33% (21% children and 12% older people), while a country like Niger in north Africa has a dependency load of 52% (49% children and only 3% older people). You can imagine the difficulty that a country like Niger would have in trying to support the more than half of its population that is dependent.
Turn to page 177 landscapeRefer to Q. 27 (a) – Begin this question by constructing a population pyramid for Japan. Refer to Figure 7.28 for your data information. Use landscape form. Label the population pyramid at the top of the page – Japan (1997). Next, Count over 28 squares and draw a line from the top of the graph to the bottom. Draw a line from the bottom of line 32 upwards. Between these two established lines are your age groups. Every two rows equals an age group, starting at 0-4 and finishing the pyramid at 80+). On the left-side of the pyramid is your male percentages, and on the right-side of the population is your female percentages. On either side of the age group bar in the middle, each line going over is.25 percent. Start at zero (age group lines). Materials: (1) Use the graph paper that has been provided. (2) You will require two colour pencils. Use one colour to shade in the bars for male percentages on your pyramid. Choose an additional colour to shade in the bars representing the female percentages.
Age-sex Distribution for Japan (1997) % Male Age Group %Female 2.40-42.3 2.55-92.4 2,910-142.8 3.315-193.1 3.920-243.7 3.925-293.7 3.330-343.2 3.135-393.1 3.340-443.3 4.345-494.3 3.450-543.5 3.255-593.3 2.960-643.1 2.565-692.8 1.870-742.3 1.075-791.7 1.180+2.2
Turn to page 178 Once you constructed the pyramid for Japan, using the data in Figure 7.28 on page 178, construct a population pyramid for Malawi. Follow the steps used in the instructions for constructing the population pyramid fro Japan. In counting over from the age groups, count each block as.5% instead of.25%. Once completed, answer Q. 27 (PARTS B, C, D, and E) for the population pyramids for Japan and Malawi.Once completed, answer Q. 27 (PARTS B, C, D, and E) for the population pyramids for Japan and Malawi.
Age-sex Distribution for Malawi (1997) % Male Age Group %Female 8.50-48.4 7.65-97.6 6.910-146.8 5.915-195.8 4.920-244.7 3.925-293.7 2.830-342.8 2.135-392.2 1.640-441.9 1.445-491.7 1.150-541.4 0.955-591.2 0.760-640.9 0.565-690.7 0.370-740.5 0.275-790.2 0.180+0.1
The Demographic Transition Model The Demographic Transition Model attempts to show how population changes as a country develops. The model is divided into four stages. Stage 1 Birth rate and death rate are high - low natural increase - low total population Stage 2 Birth rate is high - death rate is falling - high natural increase (population growth) Stage 3 Falling birth rate - low death rate - high natural increase (population growth) Stage 4 Birth rate and death rate is low - low natural increase - high total population
Population Changes in LDCs The populations of less developed countries (LDCs) are growing very rapidly. Most are at stage 2 and 3 of the Demographic Transition Model. They have declining deaths rates and high birth rates. Therefore, natural increase is high. Death rates are declining because of improvements in sanitation and healthcare.Death rates are declining because of improvements in sanitation and healthcare. Birth rates are high for a number of reasons:Birth rates are high for a number of reasons: Lack of family planning education or contraceptives In rural areas children are needed as labour on farms. In urban areas they are needed to work in the informal sector to earn money for their families. Women have a large number of children as there is a high level of infant mortality Culture/religion mean it is unacceptable to use contraceptives
Population Changes in MDCs In most MDCs population growth is stable. MDCs have low birth and death rates. In some countries (i.e. Germany) the birth rate is actually lower than the death rate. This means there is a decrease in population versus a natural increase (Germany is -0.1%). The major problem for many MDCs is an ageing population. Life expectancy in MDCs is increasing as people are now living longer due to improvements in health care, diet and lifestyle. Therefore, there will be a a greater number of elderly dependents. In the UK this is likely to lead to increased taxes to pay for health care and pensions.