After my recent blog on pie charts, (I said I was not fond of them) I was asked by a few people: "So if you don't like pie charts - what's the alternative?"
Well, that depends on the data you’re presenting. Remember, you want to be telling a story with your data so picking the right chart for the story you’re telling is important.
Below I have an example. I want to compare sales by country for 2 years: 2006 and 2007, and figure out which countries have had lower sales and by how much. All these charts are created from CALUMO’s Visual Data Discovery.
Here is the pie chart version of the data I have:
Using pie charts:
Some alternatives to these charts are stacked bar and column charts, such as those below.
You immediately get a sense of total scale difference between the years. The pies above just don't give you a sense of the decrease in performance over time, due to a pie chart typically always representing 100% - regardless of the size of the sum of the parts.
Using the stacked charts, the reader also get a clearer picture of the difference between sales in each country. The story is visually represented, and the shortfall is clear.
An unstacked chart shows how each country is doing comparatively by time and country.
I like this waterfall chart. Why? The gray bar on the left shows total sales for FY 2006 and the gray bar on the right is total sales for FY2007. The bars in the middle (red and green) are the difference in sales for each country from 2006 to 2007. The United States is a red bar and red shows negative growth. This means they sold less in 2007 than in 2006. Australia is the same, fewer sales in 2007 when compared to 2006. Any green bars means more sales when compared to last year. So the combination of red and green bars is the total increase in sales from last year (in this case a decrease). The picture is pretty clear and helps me tell my story – the US and Australian sales suffered in 2007 when compared to 2006 sales.