81  Encoding Continuous Variables

The optimal encoding of continuous variables uses a common scale, such as multiple dots in a scatter plot on common X and Y axes. Less useful encoding elements are area, angle and length without a common scale1. The least useful encoding element is the colour spectrum, however there are some exceptions (see discussion on page pageref sub:Smoothed-scatter).

  • 1 Area, angle and length are used with pie charts, which is primarily why they are not recommended.

    • Figure 81.1: Elements for encoding continuous variables.