13.3 Representing statistical data on graphs and charts
Statistical data can be represented in many ways. This section contains a variety of charts and graphs that could be used in the Geographical Investigation. You may also be asked to draw, read and interpret them in an exam.
1. Pie charts and doughnut charts
Pie charts and doughnut charts show the proportions of parts to the whole. In Fig. 9, the pie chart emphasises the proportion of bedload shapes at different sites along the river. Pie charts are used to emphasise important elements. Doughnut charts are similar to pie charts but contain more than one set of data.
PIE CHART
Very angular 13%
Sub-rounded 27%
Sub-angular 7%
EXERCISE
Examine Fig. 10. What was the value of taxes from petrol in Year 1 and Year 2?
Fig. 9 Pie chart 2. Bar charts/graphs
Bar graphs can be drawn horizontally or vertically. This type of graph is very useful when comparing two or more similar items. Data can also be grouped. In the example below, the bar graph shows the percentage of retired people living with a severe illness, an illness or in need of frequent hospital care.
VERTICAL BAR CHART
%
Fig. 11 Vertical bar graph showing the percentage of retired people in the USA with an illness and their age.
248
80– 70– 60– 50– 40– 30– 20– 10– 0–
73.6 57.7 44.946.6 30.7 28.3 8.1 10.5 % with a severe illness % with an illness 34.9 16.9 % in need of
frequent hospital care
57.7 57.6
Age 65-69 70-74 75-79 80
Angular 53%
DOUGHNUT CHART KEY KEY
Very angular Angular Sub-angular Sub-rounded
€320m €210m
Revenues from Petrol and Property Taxes
Year 2 Petrol Property
€260m €300m
Fig. 10 Doughnut chart Year 2 Petrol Property Year 2 Year 1