The above is a diagram with 4 charts. The first is the pie chart. On its right is the second one, the donut chart. Below them are the charts inspired by them, the donut ring chart. As explained in the image above, the wedges of the donut chart represent the past or target proportion and the size of the donut chart illustrates the past or target total value. Meanwhile, the pie chart's wedges and sizes show the current proportion and sum of the values. The donut ring chart can work for comparison between any 2 categories and sub-categories, but choosing which categories to be the primary chart (pie chart) and the secondary chart (donut chart) may be an issue. This is because the pie chart does seem like it takes precedence over the donut chart in this case. Perhaps, a double or more donut chart in a single space may work in this case.
Pro
1. The chart visualises comparison in addition to proportion. This chart is able to add a dimension usually not seen in a single pie chart with the power to compare on a single chart. Although placing multiple pie charts may serve the same purpose, the donut ring chart is more space efficient and display more information in the same space.
2. The chart compares the proportion in addition to all the values. Like a stacked bar chart, the donut ring chart compares 2 things at once - the proportions and the sum of values. This allows users to adjust their goals accordingly with 1 chart.
Con
1. Area is a difficult way to measure values. Similar to circle charts, the size of the total sum is visualised using the size or circumference of the circle/ ring. Without proper axes, it can only tell if the total value has become bigger or smaller, or is bigger or smaller than the targeted total value.
2. The chart is useful only probably on the first wedge. This chart has the same problem as a 100% stacked bar chart and a 100% radial stacked bar chart, the comparison can only be made meaningfully between the first wedges as they have the same starting point.
Conclusion
All in all, the donut ring chart has been another dessert chart fun to think about. This experiment does not aim to answer the criticisms of a pie chart, but it embraces the idea of the pie chart to see if another chart can be made. Labels can also be added to the charts for readers to see the percentage represented by each wedge and the values. Labels can be called out if it is too cluttered.