1.1 Dual bar charts
A dual bar chart can show two sets of data at the same time, to help readers make easy comparisons. The bars are drawn side by side.
Figure 3 Dual bar chart showing monthly rainfall in two locations, Stornoway and CamborneSource: https://www.metoffice.gov.uk/research/climate/maps-and-data/historic-station-dataSimilar formatting to that mentioned in Week 4 applies with the addition of a key being needed to clearly distinguish the two sets of data:
- Values on the axes are evenly spaced and clearly labelled, including a title showing what information each axis represents, with units of measure if applicable.
- Bars are the same width and separated with consistent gaps.
- The chart has a title describing what it shows and there is a data source referenced.
- A key is included to show what the different colour bars represent.
In a similar way, it is possible to show more than two datasets on the same bar chart (multiple bar chart), but a decision must be made about how much data can be reasonably represented on one graph.