Presenting data on line graphs and bar charts

GCSE geography exam questions often include data, which can be presented in many different ways. Two data presentation techniques that you need to be familiar with are line graphs and bar charts. This column looks at how data about life expectancy can be presented.

Figure 1 Line graph to show female life expectancy at birth in the UK over the past 30 years

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What is the difference between line and bar graphs? You might assume that a line graph or bar chart can be used interchangeably but this is not the case. Line graphs are used for continuous data to show change over time. For example, the life expectancy of a country could be plotted over 30 years. Whereas, bar charts are used to display discrete data. This means that each category has set values within it and is usually a count. For example, how many different types of vehicles were seen during a traffic count? You could also show the life expectancy in 2019 for a range of countries on a bar chart.