10/25 Age Structure Diagram

Many of the vast differences we see in societies across the globe can be related to the composition of their respective populations. This is true on the local, state, and national levels. So when exploring variations among countries, a good place to start is with their age structure diagrams (population pyramids) – graphs that display the age and sex distribution of the country’s population.

To help make population projections for different countries, demographers look at the profile of the countries’ residents. What are the ages of the people? How many are men? How many are women? Taking this information, they construct population pyramids that depict the configuration of a country’s population as impacted by 70 to 80 years of economic, political, and natural events.

This is a type of graph used by demographers to study the distribution of people across sex and age categories.

The graph represents the entire world population, sorted by age and sex – with the youngest at the bottom and the oldest at the top and males on the left, females on the right. Each age level/sex grouping is called a cohort. A cohort represents the percentage of people within that sex and age range within the population. So

on the world population pyramid, we can see that 4.5 percent of the global population is made up of

males aged 0-4.

The graph below is broken down into pre-reproductive, reproductive, and post-reproductive levels.

The shape of the age structure diagram shows if a population is rapidly growing, slowly growing, stable, or shrinking.

This graph is of Ethiopia. The triangular shape reflects a growing population.

This graph is of New Zealand. The rectangular shape shows a stable population.

This graph is of Japan. The cup shape shows a shrinking population.

Look at the age structure diagrams of these six countries to answer the following questions.