Number of lines per chart

Number of lines

The maximum number of lines plotted on a chart depends on how similar or different the data are and what you want to highlight.

You need to make sure that each line is easily distinguished from the others.

Example of chart with difficult to distinguish lines and colours

Example of a line chart showing data about religious beliefs, using a range of different colours as well as solid and dashed lines which can be hard to tell apart.

Small multiples solution

Use small multiples if it is difficult to distinguish between the plot lines of four or more similar data sets. Use the same scale for all charts when comparing two or more data series.

Example of small multiples chart

A small multiple chart showing nine individual line charts for each type of religion.

A singular time series of interest can also be highlighted, with all other data sets toned down.

Example of chart using colour and greyscale to show a singular time series

A line chart showing how to use colour and greyscale to show the differences between no religion and all other religion responses.

Slope chart solution

Use a slope chart to highlight changes between selected years. The granularity of the data is not evident, however trends are easily noticed.

Example of a slope chart

A slope chart highlighting changes in religious responses between 2005 and 2010.