Rates of Change (AQA GCSE Statistics: Higher): Revision Note

Crude Rates of Change

How do I calculate a crude rate of change?

• Understanding rates of change in a population is important for planning purposes

  • For example, a town with a high birth rate may need to think about building more schools for the increasing number of children

• A crude rate is a way to understand how things are changing in a population

  • It is often used to track births or deaths

    • But it can also be used to track other things, like marriages, unemployment, etc.

  • A crude rate normally tells you the number of births (or deaths, etc.) per 1000 people

• To calculate the crude birth rate (for example) use the formula

  • $\mathrm{crude}\mathrm{birth}\mathrm{rate}=\frac{\mathrm{number}\mathrm{of}\mathrm{births}\times 1000}{\mathrm{total}\mathrm{population}}$

    • This formula is on the exam formula sheet, so you don't need to remember it

  • To calculate a crude rate for other things, replace 'number of births' in the formula with 'number of deaths', 'number of marriages', 'number of people unemployed', etc.

• You may be given the crude birth rate (or death rate, etc.), and asked to work out one of the other values in the formula

  • If you know any two things from the formula you can find the third one

  • Substitute in the values you know

    • and solve to find the one you want to know

• You can also calculate a crude rate per 100 people (instead of per 1000)

  • Replace '$\times 1000$' in the formula with '$\times 100$'

  • Only do this if a question tells you to