- All content in charts (such as axes, keys and other labels) must display horizontally and be easy to read.
- Ensure axis labels are displayed in full and not cut off or abbreviated.
- Write out abbreviations in full or clearly explain them in the footnotes.
- Make sure there is a clear distinction between different lines, by using different line types or colour shades that can easily be distinguished when viewed in black and white – bear in mind that different colours can be more or less perceivable depending on the shape and context of the chart.
- If the axis includes dates, these must be consistently displayed for all charts in the release so that they are easy to follow.
- The key must always display above the chart for easy reference.
An interactive HTML chart should always be used rather than an image of a chart. This ensures that all users are able to read it, including those with assistive technology such as screen readers.
Interactive charts will also adapt to the size of the screen being used to view the content, so they are more useful to users accessing the content on a mobile or tablet.
Chart titles should be descriptive and clearly explain what the data are showing.
Avoid using dual axis charts as they are often misleading and difficult to understand. Either use separated charts or a single axis chart which uses annotations to explain the trends.