Age pyramid

  • Age pyramid is a graphical representation of the age – sex structure of a population
  • It consists of 2 back to back graphs, with age represented in the x axis and number of people in the y axis
  • Age groups are taken at 5 year intervals and the number of males and female in each group is calculated
  • The above data is plotted in a graph with males on the left side and females on the right side
  • The structure of the age pyramid reveals the demography of the population as a whole
  • There are various types of populations pyramids based on the relative proportion of different age groups
    • Expanding
      • with high population growth rate
      • the bottom of the pyramid is widest with the width rapidly tapering towards the top
      • indicates that there is high proportion of children and few old people
      • seen in developing countries like India
    • Stationary
      • indicates a stable population
      • the bottom is widest with the pyramid gradually tapering towards the top
      • seen in most developed countries
    • Constriting
      • the middle of the pyramid is the widest
      • this is seen when the growth rate is negative
      • the population is decreasing over time
      • some developed countries like Switzerland are in this phase

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