Americans spent almost the same amount of money on real and artificial Christmas trees in 2013. While they bought more than twice as many real trees, they paid more than double on average for artificial trees. The data comes from the National Christmas Tree Association. The two charts below show the same data in two different ways. Which do you think presents a clearer picture?
The bar mekko chart on the left and the 100% stacked bar on the right show the same data in two different ways In the bar mekko, the width of the bar represents the number of trees sold and the height represents the average price per tree. The bar area is proportional to the total retail value of trees sold. In the 100% stacked bar, each bar represents a different data set. The left-most bar shows that more real trees are sold. The middle shows that the average price is higher for artificial trees and the right shows that the total retail value is about the same for real and artificial trees. Of the two charts, I think the 100% stacked tells the story better, but it requires a little more work to produce. In Mekko Graphics, you have to adjust the labels in at least two of the bars to show that the three bars have different units. Here are the charts in SlideShare for you to download and work with: