Using dual axis charts (that’s a chart with two different y-axes represented on each side of the chart) can be very misleading. Why not to use two axes, and what to use instead makes a great case against dual axis charts. If you’re not convinced, just check out how changing the scale can tell so many different stories. The blog article also lays out some great alternatives, including:
- side-by-side charts
- indexed charts
- prioritizing and labeling (show the most important, and use annotations to add information)
- connected scatterplots
Have any other alternatives? Please share!