Concentric circle graphs are an elegant, aesthetically pleasing alternative to pie graphs. In a concentric circle graph, circles, like pie slices, separate a large circle into sections so that each section represents a proportion of collected data. Because larger circles represent more common responses and higher percentages, observers can quickly interpret the graph and process the results of the data. You can make concentric circle graphs by hand or with professional software programs.
Analyse your data and break the results into percentages. For example, if you surveyed 200 people about their favourite tree and 100 prefer oaks, 50 prefer sycamores, 40 prefer birches and 10 prefer a different kind of tree, the percentages would be 50 per cent oaks, 25 per cent sycamores, 20 per cent birches and 5 per cent "other."
Draw the first circle, using a compass or a computer program of your choice, to represent the largest response: oak trees.
Draw the second circle to represent the second largest response. The second circle must have the same centre point, or x and y coordinates, as the first circle. The second circle's diameter = first circle's radius x (second circle's percentage/first circle's percentage).
For example, if the first circle's radius is 10 units long and represents 50 per cent of the survey respondents, and the second circle represents 25 per cent of the respondents, the second circle's diameter is:
10 x (25/50) = 5 units.
Draw the third circle to represent the third largest response. The third circle -- and all other circles in the graph -- will have the same centre point as the first circle. The third circle's diameter = first circle's radius x (third circle's percentage/first circle's percentage).
In our sample graph, the third circle's diameter is:
10 x (20/50) = 4 units.
Continue drawing additional circles as needed to fully represent your data. For each circle "n," the circle's diameter = first circle's radius x ("n" circle's percentage/first circle's percentage).
Colour each section a different colour to make the information easier to process. Write or type inside each section to label it.
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