While Businessweek had an interesting infographic on the difference between correlation and causation, xkcd provides a different take on the logical fallacy of cum hoc ergo propter hoc (correlation proves causation).
In other words, correlation enables prediction whereas causation enables explanation. Correlation denotes the strength of a relationship between two variables, while causation requires correlation of cause and effect, temporal precedence and rejection of alternative hypotheses.
via Correlation versus Causation (cum hoc ergo propter hoc) « A little bit of this, a little bit of that.
Edit: Don’t forget the mouse-over text.
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