Pie Chart - GCSE Maths Definition

A pie chart is a circular graph used to show how different parts make up a whole. In a pie chart, the circle is divided into sectors (like slices), with each sector representing a part of the total. The size of each sector quickly shows the size of that part compared to the other parts.

It is crucial to understand that pie charts do not show frequencies - they only show proportion. For example, take two pie charts that both have a sector, of angle 180° (half the whole!). Both pie charts indicate that this section would be 50% of the whole, but if the first pie chart represents a total frequency of 80, the sector would represent 40; if the second part chart represented a total frequency of 10, the sector (of the same size/angle) would only represent a frequency of 5.

Pie charts are often used where actual frequencies are not immediately important, for example, when looking at how votes are cast in an election.