The American Library Association has started a new web site for the "public" called I Love Libraries. I believe the site is still under development, so for the moment it would be unfair to criticize it. For example, the site doesn’t appear to have an RSS feed. But something else caught my attention.
A long, long time ago, when I was quite young, I read a great book called How to Lie With Statistics, by Darrell Huff. One of the enduring things I’ve retained from the book is the idea of a "gee whiz graph". I don’t have to bother generating an example, since the ALA has provided a couple of them on this page (in the "Conclusions" section at the bottom).
The basic idea is that if you have a series of numbers that go from, say, 152 to 165, you can show them on a graph which has a scale from 0 to 200, and you’ll see that the values change a bit, but not dramatically. On the other hand, if you scale the graph from 150 to 170, the values will visually appear to leap from 2 to 15, an apparent dramatic increase of 650%. And that’s just what the ALA has done with the number of annual visits to libraries. Library visits increased from 1.24 billion in 2002 to 1.38 billion in 2006. This turns out to be a rate of increase of a smidgen more than 2.7% per year. In order to make this increase look more dramatic, the ALA has scaled the graph from 1.15 billion, giving an apparent increase from 0.09 (1.24 -1.15) in 2002 to 0.023 (1.38 -1.15) in 2006, a visual increase of more than 26% a year, apparently more than doubling in four years. What makes this completely inexcusable is that the graph is small and blurry, so it’s quite hard to see what’s really going on.
The other graph, showing the percent of adults with library cards, is even worse. The scale is 60% – 63% – 65% – 68% – 70%, evenly-spaced!
The ALA has clearly demonstrated two ideas that are important to its mission: you can learn a lot from a book, even one that’s 55 years old, and you shouldn’t take everything on the Internet at face value.
Books and Libraries 