In this post last month, we looked at the phenomenon called “pre-attentive processing”, an automatic parallel process within the brain that enables certain visual features to be recognised in less than 0.1 seconds. One of the most powerful features of charts that can be used to harness this phenomenon is colour.
By standardising what colours mean on our charts, we can make them much quicker and easier for our readers to digest. There are certain types of data that appear time and again on charts that can be best represented by using a consistent palette of colours.
For example, the same colours should be used to represent favourable and adverse variances. In the example below, we use blue to show a favourable variance against budget, grey to indicate an adverse variance that is less than 3% off budget and red to display an adverse variance to budget of 3% or more.
Consistent colours should be applied to represent modes when they are compared against each other. Modes are the different versions of the data such as actual, prior year, budget and forecast. Choose a consistent set of colours to designate each mode and stick to it wherever this is possible with the charts you are using.
Similarly, choose a consistent set of colours to designate particular regions, product groups, customer segments etc of your business whenever this is feasible.
Once your audience has understood the colours for a handful of charts, they will not have to spend time examining the chart legend to understand which data series are represented by particular colours. This enables them to focus entirely on the business messages of your visualizations.