That poster began with Mel (the library manager) showing Dewey (the teen services librarian) a bar chart of annual book circulation figures similar to the one shown above. She said they were circulating more books than ever. Dewey replied that chart lied because the time scale ran from right to left. (Gavin McMahon has called this mistake a TimeLord chart). In PowerPoint it isn’t hard to accidentally sort the data in only one column and wind up running the scale backward.
The data really should have been plotted with the time scale running conventionally, from left to right. Now things are looking down rather than up. In the comic the y-axis also was logarithmic rather than linear, and Dewey also added a few more refinements.
Back on November 20, 2009 I blogged about a series of Unshelved comics on introducing a speaker. From 2006 to 2010 Unshelved held an annual contest for libraries to Pimp My Bookcart.