It's almost exactly a year ago that one of my clients accused me of being responsible for the recession. He felt that spreadsheet errors had almost certainly played their part in the financial collapse and that, as someone who spends much of their time lecturing and training on the use of Excel, this was probably my fault. Then this year, in the lead up to the UN climate summit in Copenhagen, there are accusations that scientists have been manipulating data and using 'tricks' in charts to promote their own interpretations. This does happen to coincide with one of the latest Excel roadshow courses including a brief section on using charts and graphics effectively and, how easy it is to use a chart to mislead…
On the same subject, Dave Woolcock, an IT manager at Moore and Smalley, and to whom I will always be indebted for introducing me to the works of Edward Tufte, recently emailed me a copy of a letter he had sent to the Guardian newspaper concerning a chart in a recent edition had used circles to compare values. Instead of the area of the circle representing the comparative values, they had used the diameter to represent the ratio, thus making the difference appear considerably greater than it was. Here's a very simple example: which circle appears to be half the size of the larger 'green' value?
Tufte includes a chapter in his book 'The Visual Display of Quantitative Information' on Graphical Integrity and includes several real world examples of misleading charts, demonstrating how the use of areas to represent one-dimensional data can introduce a 'lie factor'. Have you been shocked by inaccurate and misleading graphics in the media or elsewhere? Please share your most brazen examples with us. Perhaps we could give a copy of Tufte's book to the person who comes up with the best(?) example during the coming year.
Anyway, briefly back to the climate change issue. There were these three adventurers driving across a big desert. Due to an error in their fuel requirement spreadsheet, they ran out of petrol in the middle of nowhere without any means of contacting the outside world. After a few days they were sitting around their camping table looking at their only remaining bottle of water. Suddenly, one of them reached across, grabbed the bottle and gulped down half of it before pouring the other half over his head to cool himself down. The others, too stunned to react in time, looked at him aghast. "What?" he snapped. "Show me the conclusive scientific proof that we’re not going to be rescued in the next hour."