Combo Charts are line charts and column charts shown together in one graph. The data can have completely different units and will have two y-axis rather than one y-axis. They are a great way to show a visual representation of your data in one graph. The examples below show the difference between a line and clustered column chart vs a line and stacked column chart. A line and clustered column charts is where the columns are shown side by side rather than stacked. It is common to show revenue and roi in a combo chart.
See the differences below:
This line and clustered column chart compares sales amounts using a clustered column chart and overlays a line graph to show the percentage differences for each month.
Of the two charts above, for this example we recommend using the line and clustered column chart since it is easier to compare the sales data values. Notice also that the latest year is on the right side, while 2015 data is on the left side. To most readers this will appear more natural since a later date should appear to the right or top.
In this example, the % difference is shown as a line graph. We can see that there was only one month, October, where sales was less than the year before (i.e dropping just under the 0% line.) We can also see that January and August performed much better than the year before.