1. Graphs

Your findings can be presented with a range of graphical and mapping techniques. You should be able to justify each one.

Bar chart

• Nominal data.
• Categories on x-axis.
• Bar height represents frequency.
• Leave gaps between bars as data are discontinuous.

There are many variations on the basic bar chart, such as divided bar chart, percentage bar chart and bi-polar analysis bar chart.

Histogram

• Interval or ratio data.
• Bar area shows frequency.
• Bars are not necessarily of equal width.
• No gaps between bars as data are continuous.

Pie chart

• Nominal or ordinal data.
• Area of circle segment represents proportion.
• Multiple pie charts can be used with the radius of the circle having meaning.

Line graph

• Ordinal, interval or ratio data.
• Both axes are numerical.
• If time is one of the variables, always plot it on the x-axis.
• Only join up the points if the data are continuous.

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Scattergraph

• This needs one independent variable (on x-axis) and one dependent variable (on y-axis).
• Both axes need interval or ratio data, and both must be continuous data.
• Do not join up each point, but use a line of best fit instead.