Population Pyramids

Also called age-sex pyramids, they show how many individuals are alive in different age groups (called cohorts) in a country or region for any given year. They also show the male-female ratio. Population numbers are on the x-axis and age groups are on the y-axis.

Types of pyramids:

• Stage 1: Expanding - High CBR, rapid fall in each upward age group due to high CDR, short life expectancy.
• Stage 2: Expanding - High CBR, fall in CDR as more individuals live to middle age, slightly longer life expectancy.
• Stage 3: Stationary - Declining CBR, low CDR, More individuals live to old age.
• Stage 4: Contracting - Low CBR, low CDR, higher dependency ratio (those that cannot work), longer life expectancy
• LEDCs tend to be in stage 1 or 2
• MEDCs tend to be in stage 3 or 4