REPRESENTATION OF DATA PICTOGRAPHS BAR GRAPHS COLUMN GRAPHS
REPRESENTATION OF DATA PICTOGRAPHS BAR GRAPHS COLUMN GRAPHS LINE GRAPHS
PIE CHART/ PIE GRAPH/ SECTOR GRAPH Religious beliefs in South Africa
Where can we use Pie charts? � They are particularly effective if there is only a small number of items to illustrate. � When data needs to be represented to allow for trends or comparisons to be recognized more easily � Sizes of categories are easily compared.
Features of Pie chart � Pie charts represent quantities as sectors of a circle. � Sector graphs use proportion to display data. � A full circle represents all of the data � The sector graph must have a title or heading. � No axes are necessary.
Calculations to find sectors of a Pie chart �A complete circle, i. e. 360°, must always be used. � Find the total data. � Each data is a fraction of the circle which is 360 degrees. Data X Total data quantity 360 = sector angle of the
How to draw a Pie chart? � Construct a circle using a compass. � Mark the centre and draw the radius. � Measure angle of the first data using a protractor. � Taking radius as base line, draw next radius which makes a sector. � Continue the same procedure till you have completed all the angles.
Example � Consider the following data which is the result of a survey where year 7 students were asked ‘What is your favourite fruit? ’.
Disadvantages of using pie chart � Only useful when comparisons are more important than the actual numerical values � Too difficult to interpret a pie chart with too many categories. � Long calculations needed to draw pie charts.
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