Choosing and reading graphs revision notes

Edexcel International GCSE Geography (4GE1), chapter 11: Geographical skills, specification point G6. Free lesson.

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Graphs present data in different ways, so choosing the right type helps you see what the data shows. Reading scales carefully and describing trends with evidence helps you give accurate geographical answers.

Which graph suits the data?

Choose a graph to match the kind of data. Some graphs show separate groups, while others show change over time or parts of a whole. A bar chart compares separate categories, such as vehicles counted by type. Its bars have gaps. A histogram shows one measurement grouped into equal class intervals, such as pebble lengths in 10 mm classes. Its bars touch. A line graph shows change over time. The points are joined. A pie chart shows percentages that make up one whole, adding to 100%. It shows shares, not the actual numbers. A compound bar is one bar divided into parts and…

How to describe a trend

Read both axes before interpreting the line. In the population graph, years run along the bottom and population is shown in thousands up the side. To read a value, go up from the year to the line, then across to the population scale. A trend describes the general direction and how the rate changes, supported by figures. The town's population rose throughout the period. It increased slowly to 30,000 in 1980, then rose faster, reaching 95,000 in 2020. A trend answer needs the direction, any change in rate, and figures that use both axes.

How to read a climate graph

A climate graph shows rainfall and temperature across the same months, but uses two scales. Read each feature against its own axis: rainfall bars against the left axis in millimetres, and the temperature line against the right axis in degrees Celsius. The hottest month is July, at 30 °C. The coolest is January, at 12 °C. The wettest month is July, with 240 mm of rainfall. The driest is December, with 10 mm. When describing climate, name the month and quote the matching figure from the correct scale.

How to plot data accurately

Plotting marks depend on accurate positions and presentation. Check the value of a small square on each axis before you mark anything.

How to read other graph types

Some graphs are read by looking at distance, direction or symbol size. Use the graph's layout and key to work out what each feature represents. A radial graph has axes spreading out from a centre, like spokes. It suits data that goes round, such as months. A point farther from the centre has a bigger value. A wind rose has bars along compass directions. The longest bar shows the direction the wind blows from most often. Proportional symbols are circles or bars of different sizes on a map. A bigger symbol represents a bigger value, using the key.