{"id":2460,"date":"2018-02-26T13:16:50","date_gmt":"2018-02-26T13:16:50","guid":{"rendered":"http:\/\/johncanning.net\/wp\/?p=2460"},"modified":"2018-02-26T16:49:44","modified_gmt":"2018-02-26T16:49:44","slug":"the-perils-of-pie-charts","status":"publish","type":"post","link":"http:\/\/johncanning.net\/wp\/?p=2460","title":{"rendered":"The perils of pie charts"},"content":{"rendered":"

NB: This post is about the problems of pie charts and is not a criticism of the hard-working people at Hailsham Town Council.<\/p>\n

A few years ago I came across Stephen Few\u2019s Save the Pies for Dessert<\/a> article on the perils (and general pointlessness of most pie charts).<\/p>\n

My local town council has just provided a gift illustration for the useless pie chart in a recent newsletter.<\/p>\n

I\u2019ll just outline some of the numerous problems with the chart:<\/p>\n

1. There is no indication of how much money will be spent in each category, so we don\u2019t know the overall size of the pie (perhaps they don\u2019t know yet).<\/p>\n

2. There are 29 categories. This means that 29 different colours are needed in the key. For example, four shades of light blue look to same to me. I don\u2019t know which slice refers to Hailsham Revitalization, which to Election Costs, which to Outdoor maintenance and which to Hellingly PC subsidy. I am not colour-blind, but I cannot tell the difference.<\/p>\n

3. Some the categories are so small they can barely be seen.<\/p>\n

4. The main thing I can decipher is most money is spent on something green, something blue and something yellow.<\/p>\n

So what is the alternative?<\/p>\n

In this case it would be preferable just to list the amount of money (or percentage of the budget) being allocated to each category. If a visual representation is really needed a bar chart would be preferable.<\/p>\n

Are there any real reasons for using pie charts?<\/p>\n

1. Some readers might understand the budget better visually, but with 29 categories they would need an incredible eyesight and and superb ability to distinguish colours.<\/p>\n

2. They might be useful where there are a small number (<5) of categories. However, the data would probably be still be better presented as a table.<\/p>\n

3. They can be very pretty and use up some space.<\/p>\n

Can it done worse?<\/p>\n

1. In black and white\/ greyscale.<\/p>\n

2. Using spreadsheet's 3D pie chart feature (It looks nice but the perspective distorts the proportions.)<\/p>\n

$\"\"$ <\/p>\n\n\n