Interesting visualisation

One of my favourite websites is TED. TED is a conference organisation that has outstanding speakers explaining a range of topics. I just came across an interesting presentaton on a technology to visualise scientific data - you can see it here.

Too many slices

If you have to use a pie chart - really there are better charts to explain data - then limit the number of segments on the pie chart to give the reader a fighting chance of understanding it.

The pie chart below is from Rio Tinto's 2008 annual report (Rio Tinto is one of the world's largest mining companies). Apart from being a doughnut pie chart, which makes cognition even harder, Rio has 10 segments they are trying to compare. Nancy Duarte in slide:ology recommends a limit of 8 segments in a pie chart. I think even 8 segments is too many and would go for a maximum of six segments.

Pretty pictures vs clear data representations

Graphic designers love to use colour and innovative diagrams to catch the readers eye. Unfortunately this can make it difficult to analyse any underlying data.

Below is a pie chart taken from the 2008 annual report for Westfield (the worlds largest shopping centre owner). Pie charts are difficult to analyse because the reader is expected to compare the differences in the angles of the pie slices. This pie chart also has a strange choice of colours with New Zealand and United Kingdom having very similar colours making it difficult to differentiate between them. The faint shadowy circle within the pie is also distracting.