A population pyramid is a graph that allows us to see the gender and age structure of a population. There are different shapes to the pyramids which tell us different things about the population of the country. It is often useful to divide population pyramids into 3 distinct age groups or COHORTS- 0-15 or the Young, 16-65 or the working age and 65+ as the retired sectors of the population. Knowing the percentage of people in these sectors can allow us to calculate a Dependency Ratio. This is the ratio between those of working age and those of non-working age. The no-working age are known as DEPENDENTS because they depend upon the working age people to provide for their needs.
