POLPULATION PYRAMID

POLPULATION PYRAMID

1. Is a bar graph in a form of a pyramid

2. Drawn to express the age and gender of a human population

3. Characteristics of Pyramid

   • Age groups are shown on the vertical scale
   • Youngest at the base
   • Age groups are usually five age groups, shown at the centre of the pyramid
   • Separated into Working Adults, Children and the aged
     • Working adults aged from 15 - 64 yrs old
     • Children aged from 0 - 14 years old
     • The Aged ages from 65 yrs and above
   • Number or percentage of males and females withing ach age group on the horizontal scale
   • The males on the left, females on the right
   • Percentage of numbers increase the the left for males, right for females

4. Factors affecting shape of population pyramid

   • Birth rate
   • Death rate
   • Migration
   • Tendency of females to outlive males

5. Describing and Interpreting Population pyramids

   • Expansive or Pyramidal-shaped pyramid
     • Wide base and tapers to the apex
     • Age groups of children become longer at the base indicating a growing youthful population
     • Broad base indicates high birth rate and high fertility rate
     • Pyramid narrows rapidly towards the top as there is a trend of declining death rate and low life expectancy.
     • Overall sex ratio is balanced
     • Little immigration or emigration
     • Typical of developing countries with an increasing population
   • bee-hived pyramid shape
     • Has a narrow base and is without a marked taper until towards the oldest age groups
     • Bars of the children are shorter towards the base
     • Narrow base implies low birth and fertility rate
     • Young dependent makes up less than 30% of total population
     • Has a broader apex than a pyramidal- shaped pyramid
     • Population is greying , average age will rise and females tend to live longer
     • Happens in developed countries

6. Population Distribution and population density

   • Population Density = Total Population / Total area
   • High population density : above 200 people per square km
   • Moderate population density : 21 - 200 people per square km
   • Low population density : below 21 persons per km