Tuesday, November 17, 2009

Doggerel #215: "It Can't Be Coincidence!"

Welcome back to "Doggerel," where I ramble on about words and phrases that are misused, abused, or just plain meaningless.

One annoying aspect I deal with in many woos is that they attempt to apply fiction logic to reality. In the movies, coincidences are evidence of the villain's conspiracy. In reality, coincidences happen all the time. Correlation does not imply causation.

Consider this scenario: Ice cream sales rise at the same time burglary does. If we were to apply movie logic to this fact, we'd be accusing dairy farms of being criminal syndicates. In the real world, we have to consider that the two things could have a common cause that creates two otherwise unrelated effects: Ice cream sales and burglaries increase at the same time: Summer. Ice cream probably sells more in summer because people want something cold to consume. Burglaries probably rise because criminals think it's easier to steal from a home when the family is on summer vacation. There may be plenty of other reasons.

Coincidence is not evidence of causation. Before we can conclude there is a causation, we need a reason to think one thing causes the other, and/or control for alternative causes. This is one of the cornerstones of the scientific method: Removing the possibility of known explanations so that we can look into as yet unverified explanations.

1 comment:

antares42 said...

Zero Comments? Not even Sir Gabriel? This Can't Be Coincidence! ;-)