The Mindset

After publishing the post Visualize Your Data, I received a mail from Tom Harris wondering why I hadn’t mentioned the book on data visualization: The Visual Display of Quantitative Information by Edward R. Tufte. I’d had a good reason for not mentioning it. I’d never read this book until that moment.

So, I followed my own advice and Tom’s recommendation and took a day to read the book. The bottom line: this book is indeed a great resource on data visualization. It is also fun to read (despite the technical title).

The chapter I liked most discussed the issue of graphical integrity, or (to be blunt) how data visualization is sometimes used to deceive the audience.

I must admit that whenever I see a graph, a diagram or another visualization of data I try to find the catch, so the concept was not new to me. However, the author had managed to present it so sharply and accurately that I found myself smiling with pleasure with every new example I encountered.

The biggest surprise for me was the mathematical definition of The Lie Factor:

Lie Factor = size of effect shown in graphic / size of effect in data

This simple formula turns the intuition that “something is wrong with that diagram” into an actual number. So simple. So true.

The same definition can be applied to any other form of communication, although not with the same degree of accuracy.

Every now and then I get to hear a speech or see a presentation which seems to leave me with a WOW impression, only to find out later that reality is not that impressive. I don’t want to sound cynical or too skeptical, but taking the Lie Factor into account might be a good idea in such events.

Of course with data visualization it is much easier. In most cases the raw data is accessible, so with awareness and a little effort you can expose a potentially false presentation. With other forms of communication this is harder to do. Still, with awareness and a touch of curiosity you will be able to look beyond the Lie Factor and get the facts right.

Back to the book: great reading and extremely important to anyone who wants to make a point using data. Honestly.

This entry was posted on Friday, May 26th, 2006 at 2:41 pm and is filed under Honesty, Metrics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.