## Which graph should I use?

The four most common types of charts of graphs used in school science are:

**Pie chart**

This is a circular chart divided into sectors. The area of each sector is proportional to the quantity it represents. Together, the sectors create a full circle. Pie charts are used to display data when the intention is to display the breakdown of frequencies of the variable value as a relative percentage of the whole.

**Bar graph**

A bar chart has axes and rectangular bars with lengths proportional to the values that they represent. Bar charts are used for comparing two or more values. The bars can be horizontally or vertically oriented. Each bar in the graph may represent a set of data which has been calculated and summarized into a single representative figure such as an average.

**Line graph**

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A line graph uses a curve to show changes along the time axis or changes resulting from the effect of one variable on various variables in an investigation. It is constructed within the framework of an axis. A reasonable number of data points are required to enable the drawing of a smooth curve and to allow the extrapolation of the data to the axis.

**Scatter graph**

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A scatter chart uses Cartesian (x,y) coordinates to display data as a collection of points. It shows the data points scattered between the axes. It is often used as a quick check to see if there is a relationship between two different variables and therefore maybe constructed as data is collected during an investigation.