Maths everywhere

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# Packaging the pictures

Here's Example 2 again.

## Activity 7

Study each of the five statistical diagrams that make up Example 2. Write down, in one or two sentences, your interpretation of the information that each diagram displays.

What's in your dustbin’ (the pie chart) shows the percentage of packaging materials in an average UK dustbin: 7.5% glass, 5% paper, and so on. It also shows that 75.25% is non-packaging.

‘How much is recycled’ (the line graph) shows that the percentage of materials recycled is increasing. It is highest for glass, at 60%, and lowest for plastics and paper (about 10%). Notice, however, that the horizontal scale is not evenly spaced. Does this distort the graph unreasonably?

‘German ambition’ (a bar chart) shows Germany's aim to collect and recycle different materials. Although comparisons between the different materials are shown, it does not make clear what the percentages are part of. For example, 60% of what glass is collected?

‘How much’ (a bar chart) shows the quantity of packaging materials used in the UK (in millions of tons); paper (industrial) is the largest.

‘Could do better’ (a bar chart) compares the percentage of glass recycled in different Western European countries in 1992. The Netherlands is highest at about 75%; the UK and Greece are low with about 20%.

Graphs and diagrams offer thought-provoking ways of displaying quantitative information. Often the most effective way of describing and summarizing a set of numbers is to use images related to those numbers. Of course, the newspaper could have chosen to represent the information about packaging using tables of numbers, but the diagrams are certainly more eye-catching and make patterns more obvious. For example, the UK's low percentage of recycled glass in ‘Could do better’ is shown much more clearly than it would be if only the numerical percentages were displayed.

However, like numbers, graphs and diagrams are abstract representations that summarize certain aspects of the world in a very condensed form. Unlike photographs which provide a ‘true’ likeness, their interpretation requires a degree of mental effort on the part of the reader. Although a picture may sometimes be worth a thousand words, a poorly designed one merely obscures the underlying message.

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