Proportional data chart
Your data may be showing percentages or a part or share of something, eg in a class of 30, there may be 15 boys and 15 girls. This means that in total there are 50 per cent boys and 50 per cent girls (which equals 100 per cent).
This is known as proportional data.
Pie charts
The best type of chart for proportional data is usually a pie chart.
Pie charts work well when there are small numbers of proportions or categories, as too many make the pie chart look overcrowded.
Example
Students have been asked to say whether they strongly agree, agree, disagree or strongly disagree with the following statement.
Mobile phones should be allowed in schools.
Begin by entering your data into a spreadsheet.
Then click on the pie chart button in the tool bar and you will be able to create a pie chart.
In a pie chart, it isn鈥檛 possible to have titles for each axis, as no axis appears in this type of chart. So a key is needed instead. The key shows what each section is representing. In this example, the red section is showing the proportion of students who agree that mobile phones should be allowed in schools. Twenty-five per cent of students agree with this statement.
Recap
- When producing any chart, it must have a title that summarises what the graph shows.
- For bar charts and line graphs, there should be both an \({x}\)-axis (eg age, year, distance) and a \({y}\)-axis (eg millions, height).
- For pie charts, there should be a key showing what each section represents.