Excel has the ability to graph data with different number scales on the same graph. You can do this by adding another axis to the graph. This is helpful when you have two data sets that you want to plot together, but have large discrepancies in scale.
To illustrate, let’s take some box office data. Our data set shows the US and Canada box office totals in millions. We want to compare that to the average movie ticket price. Because the scales are so different, if we try and graph these together, it doesn’t produce useful data:
To add a secondary axis to the graph, select the graph. Two Chart Tools ribbons will appear. On the Design ribbon, click the Change Chart Type button.
In the options, select the Combo graph at the bottom. This option will show each data set. You can choose a different chart type for each data set. In addition, you can pick one of the data sets to be graphed on a secondary axis. By clicking in one of these boxes, the graph scale will change.
The graph now shows a better relationship between the two data sets, despite the discrepancy in scales.
