Years ago, Andrew Abela created this simple, clear diagram:

I love it. I am surprised at the frequency that I see poorly presented data. Often, it boils down to a chart choice that's just plain wrong. Hmmm, this chart sure sure is shiny... I think I'll use it! you think as you scroll through the myriad options in Excel. Future Edward Tuftes, Richard Saul Wurmans, and talented designers aside, most of us are clueless when it comes to effective data presentation. With this at our side at least we can start off on the right foot!