Which of the following is a primary use of age structure diagrams in demographic studies?

• A. They help predict future population changes by revealing age-and-sex distribution
• B. They measure air quality
• C. They display annual crop yields
• D. They show historical climate data

Answer: (A)

Age structure diagrams show how a population is distributed across age groups and sexes, which is essential for predicting how the population will change over time. A broad base signals many young people and potential rapid growth as these cohorts reach reproductive age, while a tall, narrow top suggests an aging population that could eventually slow or decline. By revealing the size of those cohorts and the balance between sexes, these diagrams help estimate future birth rates, aging trends, and the overall trajectory of population size and dependency on the working-age population. The other options aren’t about people or age, so they aren’t answered by age structure diagrams.