Visual explanations

Over the weekend my local newspaper syndicated a Washington post story about the challenges that Microsoft is facing. It included a large infographic which caught my eye. For Christmas I got two of Edward Tufte's books that I've read but never owned: The Visual Display of Quantitative Information and Visual Explanations. After rereading them, it's painful to look at newspaper and magazine infographics.

In this case the first thing to jump out at me was the photo caption that read: "Bill Gates in 1984. He was 35 when Microsoft went public two years later." No, he wasn't. He was born on October 28, 19551; Microsoft went public March 13, 19862; Gates was 30 on that day, not 35.

The charts were more insidiously misleading. Here's a comparison intended to show that Google's post-IPO growth outpaced Microsoft's:

Rearranging the charts in this side-by-side way, as opposed to the up-and-down treatment in the original infographic, highlights one of the problems here. Microsoft's post-IPO period included the October 1987 stock market crash. Right before that happened, Microsoft was up 467% as compared to Google's 402%.

The up-and-down treatment is useful in another way, though. It underscores the fact that two different periods are being compared: 499 days for Microsoft, 658 for Google. Normalizing the span in either direction gives quite different results.

In addition to these problems of interpretation, there's another factual error. The 318.6% gain reported for Microsoft is just wrong. It was really 292%.

Finally, the sales and profit comparisons don't adjust for inflation.

It's hard to get this stuff right, and mistakes will be made. My point is twofold. First, that we all need more and better tools to help us create and analyze these visual explanations. Second, that the natural home for such tools is online. We should expect to find much more there than static PDFs of the printed infographics. The data, as well as the interactive tools used to analyze the data, can and should be online. It should be straightforward to verify facts and explore alternate interpretations. Here's hoping that 2006 brings some progress on this front.

1 Despite the battleground nature of this subject, by the way, Wikipedia has it right, and also helpfully sources the official bio.

2 Wikipedia gets that right too; Microsoft's site confirms.

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