In 2017 I was in Birmingham with the Alabama Power Company’s grantees. We spent two days learning data visualization principles and producing makeovers of their graphs.
Before: One of the grantees was presenting their revenue and expenses in two pie charts. These numbers can’t stay in a pie chart because a) there are too many slices, b) you can only show one pie at a time – not two beside each other, and 3) pie charts are only useful for showing a single snapshot in time (this group needed to compare quarterly spending, and pies can’t really show trends over time).
After, the bare minimum: At the very least, we need to convert the pies into bars.
After, a little more useful: I annotated the graph so that the organization’s leaders would know the total revenue and total expenses.
After, much more useful: I designed a one-page dashboard that placed the quarterly numbers directly beside each other to make comparisons natural and easy.