Through our class and blogs, we have discussed as to why pie charts are best left alone. One of the reasons for avoiding pie charts is the difficulty in judging the area of each slice, since it is dependent on the angle at the center. So the question now is, if we were to remove the angle element from a pie chart, would the resulting chart be more useful?
To start answering this question, let’s first identify a name for this resulting chart and look at some of its characteristics. The resulting chart is called a Square Pie Chart or more commonly known as a Waffle Chart. The waffle chart is represented as a square/rectangular block consisting of small tiles. Each tile in the block contributes to the entire sum/percentage of the block and is weighted equally. Therefore, the waffle chart manages to provide a balance between the visual aspect and the ability to synthesize the data. The biggest advantage of using a waffle chart, over a pie chart, is the ability to synthesize data down to 1%. This is possible by comparing the various parts (area) of the waffle (which in most cases is a square, thereby making calculations easy – number of cells in row multiplied by number of cells in column). Even when compared to a bar chart, a waffle chart looks more interesting and can answer questions such as “x is y times greater/smaller than z”.
However, just like in the case of a pie chart, we need to be cautious when deciding which visualization to use. The critical factors to keep in mind will be the number of categories being described and the value difference between each measures. In addition to these two factors, we also need to tailor the visualization according to the audience, the context/setting, and the message being delivered.
References:
http://tableaulove.tumblr.com/post/56368410545/yummy-yummy-tableau-waffle-charts-from-jesse
http://bl.ocks.org/XavierGimenez/8070956
https://community.tableau.com/thread/125926
http://junkcharts.typepad.com/junk_charts/2008/06/the-right-scale.html