Population structure refers to how a population is grouped by age and sex. It is summarized using a population pyramid. To interpret a pyramid, you look at the base to see recent trends, the top to see life expectancy, and the middle to see if any age groups stand out. The dependency ratio is calculated by dividing the non-working population (ages 0-14 and 65+) by the working population (ages 15-64). This ratio is directly linked to a country's population structure.

2. Interpreting Pop Pyramids Start at the base – what has happened recently? Next go to the top – how long do people live for? Then look at the middle – are there any age groups that stand out? Long / short bars?

3. Dependent Population

5. How has the population structure of the UK changed over time?

6. How has the population structure of the UK changed over time?

7. How has the population structure of the UK changed over time? Male Female Population in millions

8. How has the population structure of the UK changed over time?

12. http://news.bbc.co.uk/1/hi/uk/4045261.stm

13. The worldwide distribution of people aged 65 and over