Population Pyramids
What are Population Pyramids and what do they show? Bar graphs used to show the age and sex structure of a population Vertical axis: Represents various age groups Horizontal axis: Shows either the actual number or the proportion of the population for both males and females Each population pyramid represents 100% of a particular population
Expanding population pyramids Show larger numbers or percentages of the population in the younger age groups, usually with each age group larger in size or proportion than the one before Population growth is rapid Base is wide means: High birth rate= ‘young’ population
Contracting population pyramids Displays lower numbers or percentages of younger people Low birth rates Upper part is wider: ‘Ageing’ or ‘old’ population
Stable population pyramids Displays somewhat equal numbers or percentages for almost all age groups Smaller figures are still to be expected at the oldest age groups Population growth is neutral or stable http://www.destatis.de/bevoelkerungspyramide/ http://www.abs.gov.au/websitedbs/d3310114.nsf/home/Population%20Pyramid%20-%20Australia
Fluctuating population pyramids Shows larger numbers or percentages of the population in some age groups, and smaller in other age groups Possible reasons: Effects of war and/ or migration
Expanding influx of young males population pyramids Population Pyramid United Arab Emirates 2005 Displays a high number of young males and only a small number of females in comparison Possible reason: Mining town- influx (arrival) of economically active males
Rural out-migration of young males population pyramids
Rural out-migration of young males population pyramids Displays a smaller number of economically active young males, who often return to the countryside when they have earned sufficient money Rural population= mostly young children, women and old people
How to Read a Population Pyramid Width of the Base (children between 0-14 years old) Birth rate varies with the width of the base Wide base indicates a high birth rate Narrow base indicates a low birth rate
How to Read a Population Pyramid Width of the Middle (working adults between 15-64 years old) Wide middle indicates a high number of economically active people Narrow middle indicates a low number of economically active people
How to Read a Population Pyramid Width of the Top (older/ retired people 65+ years old) Wide top indicates an aging population Narrow top indicates lower life expectancy
How to Read a Population Pyramid Symmetry Ideal: pyramids should be relatively symmetrical Any asymmetry indicates a difference in the male and female population Example of Russia 2011: pyramid shows more females at age ranges above 50 which indicates that women are living to older ages than males
How to Read a Population Pyramid Shape of Sides Curved in sides indicate a high death rate Slightly rounded sides indicate a low death rate Example Haiti 2011: population pyramid exhibits curved sides indicating a high death rate
How to Read a Population Pyramid Bumps in the sides Irregularities in the sides indicate a demographic anomaly Example USA 2000: 30 -50 age group in the population pyramid at the right represents the baby boom; this bump will travel upward as the baby boomers age Example Bahrain 2011: large numbers of working aged men in the pyramid to the left indicates a migrant workforce