You often want to drill down to show the detail in a specific chart segment. Here’s an example from McKinsey that uses horizontal stacked bar charts as a drill down for a simple stacked bar:
The left-hand chart shows spending by region of the US Ski Association. It’s split between allocated association expenses and regional expenses. You can see the the Eastern Region has the most expenses and a large proportion of its expenses are allocated from USSA.
The two right-hand charts drill down into the components of the allocated and direct expenses for the Eastern Region. These simple horizontal stacked bars provide an excellent means for drilling down. I used a similar color palette and linking lines in PowerPoint to connect the summary data with the detail.
Here is the slide in SlideShare for you to download and edit: