SHS Maths | shsmaths.com Pie Charts GCSE Statistics

Pie Charts Intro We use pie charts went you want to show the relative proportions of something – how one amount compares to another – rather than show the actual frequencies. The angles in a pie chart add up to 360 o Key things to work out:  What angle does one person represent?  How many people does each degree represent?

Key things to work out:  What angle does one person represent?  How many people does each degree represent? BreakfastAngleFreq Fruit2 Cereal Continental5 Full English

Drawing a Pie Chart Draw the circle Mark the centre Draw a ‘start line’ – vertically from centre to top. Draw the first sector from this start line Draw other sectors, add title, labels etc. and check.

Comparing Pie Charts Pie charts which represent different total frequencies need to have different total areas. This means that pie charts with different total frequencies need to have different radii. (radiuses!) If they didn’t the charts could be misleading.

Here are two pie charts showing the GCSE scores from two schools. Which school has done better? Actually – it is unfair to compare them like this as the frequencies are different. Instead, we need to adjust them for relative area.

To adjust for area:  If chart 1 has F1 people in it, and chart 2 has F2 people: You need to learn this!