A circle graph is best used to represent what kind of data?

Answer 1

Taking a "circle graph" to mean a pie chart, it is best used to represent shares - or parts of a whole.

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It works as a comparator, usually of percentages, by readily-visual areas, but it is normal to show the figures as well so it makes sense. Its typical uses are illustrating social statistics of one sort or another, or summarising budgets, in readily-visible ways.

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There is another type of circular graph I am surprised not mentioned on Answers as far as I have seen: the Polar Graph, which is the rotary equivalent of the Cartesian line graph. Don't confuse it with Microsoft Excel's cack-handed "Radar Chart"! The Polar Graph shows amplitude versus angle so can be read numerically in fine detail, and finds many uses in science and engineering where the Pie Graph is not appropriate and the Cartesian Graph would work but is not realistic.

Three examples: The directionality of a microphone. The true radar image, of distance v. bearing. The special case of the speed v time-of-day graph over 24 hours on the tachograph card used to record the journeys and drivers' work / rest times of a heavy good vehicle or bus. This last could be rectangular but it is far easier to use a small rotary plotter within the speedometer's cylindrical body.

Answer 2

Taking a "circle graph" to mean a pie chart, it is best used to represent shares - or parts of a whole.