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Geography

Graph skills

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Often the best way to represent numerical data [data: information without context, eg a list of students with numbers beside their names is data, when it's made clear that those numbers represent their placing in a 100 metre race, the data becomes information ] is in a graph. This makes it easy to read, digest, compare and spot trends. Different types of graph are used to present different types of statistical information.

# Graphs 1: line graphs

Different types of graph are used to represent statistical data [statistical data: Information in numerical form, usually presented in tables. ]. The most common types are line graphs, bar graphs and pie charts.

Most graphs have two axes: the X axis is horizontal (across the bottom) while the Y axis is vertical (up the left side). The two axes each represent a different set of data [data: information without context, eg a list of students with numbers beside their names is data, when it's made clear that those numbers represent their placing in a 100 metre race, the data becomes information ]. Line graphs are drawn by plotting points by their X and Y coordinates, then joining them together or drawing a line through the middle.

The line graph below shows how energy consumption is expected to rise, while consumption of fossil fuels [fossil fuel: Fuels such as coal, gas and oil which are mined from the earth and burned to produce energy. They are formed from broken down animals and plants that died a very long time ago. ] falls and the demand for renewable [renewable: A resource which is generated from sources which are not finite or exhaustible. For example, wave power, wind power, solar power or geothermal energy are renewable energy sources. ] energy increases.

Graph showing demand for energy

## Types of line graph

### Comparison

Sometimes different sets of data will be represented on the same line graph, so comparisons can be made. This is sometimes called a comparison line graph.

### Compound

If information can be subdivided into two (or more) types of data - eg total population growth, female population growth and male population growth - then all three can be drawn on a compound line graph.

### Scatter

Where the points on a graph do not map into a neat line, a line is drawn through the middle of the points to show the trend or correlation. This is called a scatter graph.

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