Better than a thousand words

I’ve just finished studying some of the work of Edward Tufte, a professor at Yale University, who teaches courses in statistical evidence and information design. Not a promising subject you might think, but it’s fascinating. Here are two of Tufte’s stories about the potential of excellent visual explanations.In the US in 1987, John Gotti was acquitted of Federal racketeering and conspiracy, after a seven-month trial. A fundamental weakness in the case was the prosecution?s reliance on evidence from criminals. This was brought home to the jury by a simple chart.

Written across the top were the names of seven principal prosecution witnesses. Down the left hand side of the chart were listed 69 crimes, including murder, heroin possession and sale, and pistol whipping a priest.

Finally, the chart was marked with thick black crosses indicating which crimes had been committed by which witnesses. The resulting forest of black crosses persuaded the jury not to rely on the evidence of those witnesses.In 1986, seven astronauts died when the space shuttle Challenger exploded shortly after its launch. Two small components ? rubber rings in the craft leaked.

They had lost their resilience because of the very low temperature that day. The day before, the engineers had opposed the launch. They had faxed 13 pages of information to NASA to support their worry about the stability of the rings when cold, but were unconvincing.

In Tufte’s view, if they had shown the whole history of ring failure, if they had given weightings to the different degrees of damage and had shown this evidence against the temperature when the launches were made, the increasing problems with the rubber rings at lower temperatures would have been clear. With launches above 75øF there had been no problems; at the coldest launch to date, 53øF, significant problems had developed. The fatal launch was at 29øF.Clarity creates understanding and understanding encourages action. What might we comprehend from a visual presentation of Nick Leeson’s transaction records and Barings? cash flow in the months before the fall?

Ann Baldwin, FCA, is a management trainer and conference speaker

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