Pie Chart

Pie Chart By Lydia Bunsu Jessica Jannet Anak Ahi

What is ‘Pie Chart? A pie chart (or a circle graph) is a circular chart

divided into sectors, illustrating relative magnitudes or frequencies.

In a pie chart, the arc length of each sector (and

consequently its central angle and area), is proportional to the quantity it represents.

Together, the sectors create a full disk. It is named

for its resemblance to a pie which has been sliced.

This is what ‘Pie Chart’ is looks like:

The above figure is a pie chart of populations of

English native speakers.

Discussion on use  Statisticians tend to regard pie charts as a poor method

of displaying information.

 They suggest that length is a better scale to use, since

perceived differences would be linearly related to actual differences.  However, if the goal is to compare a given category

(a slice of the pie) with the total (the whole pie) in a single chart and the multiple is close to 25% or 50%, then a pie chart works better than a bar graph.

This is why pie chart is not suitable for some cases…  It is more difficult for comparisons to be made between the size

of items in a chart when area is used instead of length.

 Three sets of data plotted using pie charts and bar charts.

How to make a report based on given Pie Chart? It is up to you how to make a report based on given

Pie Chart. But, you have to include all these point into your report: The title of the pie chart (what is the pie chart is all

about). State the major segment of the pie chart. The largest section, the smallest section, others section (include the percentage). Conclusion on the pie chart.

Example of Report based of given Pie Chart…

(title of the pie chart)The pie chart is about the world rubber production in 1970. (major segment)According to the statistics given in the pie chart before, we find that there are three major rubber producers in the world. They are Malaysia, Indonesia, and Thailand. (percentage)Malaysia leads as the largest rubber producer in the world, producing about 38 % of the world’s rubber. Second comes Indonesia with 33% and finally Thailand with 20 %. Other nations like Sri Lanka and Vietnam, for instance, produce only amounts as small as 6 % and 3% respectively. (conclusion)All the leading rubber producing countries mentioned above are located in the South East Asian region where the climate is found to be suitable for the growth of rubber tree.

Pie Charts Construct a pie chart from a collection of data, using a protractor.

Makes of car in a school car park

Construct a pie chart to show this information. A full circle is 360o There are a total of 3+2+4+1 = 10 cars We use 36o to represent each car

360o

Work out the missing numbers on this number spider 12 90

30

÷4

÷ 30 ÷ 12

4

÷ 90

360

÷ 24 ÷ 20

÷ 15 24

15

÷ 10 36

18

Makes of car in a school car park

3x36o =108o

2x36o =72o

4x36o =144o

1x36o =36o

We use 36o to represent each car so the 3 Cavaliers are represented by 3x36o = 108o Work out the angle needed for each of the other models of car

Makes of car in a school car park

Mark the centre of the pie and draw the circle. Draw a line from the centre to the edge Measure the first angle needed (108o) Draw in the line and label the section

Cavalier o 108

Makes of car in a school car park

From this line measure the next angle, draw the line and label the section.

36o Volvo

Cavalier

Continue in this way Check that the last section has the correct angle and label it.

Rover 144o

72o

Ford

Why? Why do we use 36o to represent 1 car? What would happen if there were 20 cars? What about 60 cars? Or 15 cars?

If there were 20 cars in your survey, what angle would you use to represent 4 cars? 7 cars? 12 cars?