A pie chart, or circle graph, is a type of graph that shows how different parts relate to a whole. If you have a questionnaire about the political affiliations of a group of voters, you can make a pie chart showing how many voters fell into conservative or liberal categories. You can make a pie chart from any type of questionnaire as long as the questionnaire can divide your data into categories.
Decide what categories you want to graph. Study your questionnaire and determine what categories the questions fall into. For example, if your questionnaire is about animals in households, you might have "Dog," "Cat," and "Fish" categories.
Count how many questionnaires fall into your categories. For example, out of 120 questionnaires you might have 60 questionnaires from dog owners, 30 from cat owners, 15 from fish owners and 15 from "Other."
Convert the number of respondents in each category into a percentage of a whole. For example, 60 out of 120 = 60 / 120 = 50 per cent, 30 out of 120 = 30 / 120 = 25 per cent and 15 out of 120 = 15 / 120 = 12.5 per cent.
Convert your percentages into angles by multiplying 360 degrees by the percentage. For example, 0.5 x 360 degrees = 180 degrees, 0.25 x 360 = 90 degrees and 0.125 x 360 = 45 degrees.
Draw a circle on the paper with the compass.
Draw a horizontal line across the centre of the circle to make two halves.
Draw a vertical line across the circle from the top to the bottom, making four quarters.
Draw two more lines going across the circle through the centre in the shape of an X, dividing the circle into eight equal pieces. Each piece represents 45 degrees.
Choose a colour and colour in the first category. In this example, the Dog category is 180 degrees, so colour half of the circle in your chosen colour. Outside the circle, draw a small box and write the name of the category next to the circle. This is the graph's key. Repeat, using a different coloured pencil, for the rest of the categories.
- A circle graph is a representation or model; it doesn't have to be exact. In other words, if you have a number of degrees like 12.99 or 34.35 to graph, just take your best guess at what size segment that would cover.