Correlation != Causation

(from PeteSearch)

My dog Thor hates getting wet, but even when there's rain lashing against the windows he still starts off dancing in circles when it's time for his walk. It's only when I pull out his yellow rain jacket that he slumps and stares at me mournfully. He seems convinced that if I just left the jacket off, the rain would go away.

Much as I try and convince him of the error in his logic, he's unmoved, and it's hard to blame him. Humans will happily swallow studies that use the weasel word 'link' to claim something that is associated with an outcome is its cause … I half-expect to get up one morning and discover that Thor's eaten the raincoat, in the hope of bringing back the sun …