3.3 Comparative bar charts

A comparative bar chart places bars representing sections from the same category adjacent to each other. This allows for a quick visual comparison of the data.

For example, another way of categorising the data that you have been working with so far would be to split each nationality into the number of females and males. The resulting comparative bar chart would be as shown in Figure 17.

Figure 17 Comparative bar chart showing the gender of hotel guests

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This vertical bar chart has the same axes and source as the previous chart. However the title reads ‘Male and female guests at hotel’ and the key shows two categories male and female. For each category, there are two bars next to each other, the left hand bar represents the male guests and right hand bar represents the female guests. For the Irish category, the top of the left-hand bar is opposite the 10 on the vertical scale and the top of the right-hand bar is opposite the 7. For the British category, the top of the left-hand bar is opposite the 4 on the vertical scale and the top of the right-hand bar is opposite the 10. For the mainland European category, the top of the right-hand bar is opposite the 2 on the vertical scale and the top of the left-hand bar is also opposite the 2. For the rest of the world category, the top of the left-hand bar is opposite the 5 on the vertical scale and the top of the right-hand bar is opposite the 7.

Figure 17 Comparative bar chart showing the gender of hotel guests

It is easy to see why this is called a comparative bar chart, as it is straightforward to compare the data – for example it is easy tell that many more visitors from Britain were female.

Finally in this section on bar charts, notice how all these charts followed the same format, with the title and source clearly labelled and the axes and scales clearly marked, but they emphasised different aspects of the data. The first showed the totals from each nation, whilst the latter two gave more detail on this data. So when you are displaying data in a graphical form, it is important to choose a chart or graph that stresses the main points as simply as possible so that your reader can understand your chart quickly and easily.

Now it’s time to look at our final type of chart, the pie chart.