A cartoon suitable for use in teaching the idea that association does not imply causation. The cartoon is number 552 (March, 2009) from the webcomic series at xkcd.com created by Randall Munroe. Free to use in the classroom and on course web sites under a creative commons attribution-non-commercial 2.5 license. A t-shirt with this cartoon is also available for sale at xkcd.com.
- Prof Dev