The Correlation/Causality Puzzle, Peanut Butter Edition

We’ve written often — most recently here — about the fact that just because two things are correlated, it does not necessarily follow that one causes the other. For instance: campaign spending and electoral success; “culture cramming” and childhood test scores; the use of child car seats and the decline in auto fatalities.

So it was interesting to see, on a subway ride yesterday, this poster from America’s Peanut Farmers:

Do we forget about peanut butter when we get old, or do we get old when we forget about peanut butter?

Great slogan. The only problem was that the sandwich on the poster, which I gather was meant to be a peanut butter-and-jelly sandwich, instead looked like scrambled-egg-and-ham sandwich. That sort of killed the effect.