[1shooner]

When I first heard the clinical idiom "When you hear hoof-beats, think horses not zebras" I thought it was a precautionary saying about the bias toward assuming the familiar. But it's meant to be instructive!

[TylerE]

No, that’s backwards. It means what it says. When you see a symptom first look for the common things it could be, not the one in a million chance.

[jxjnskkzxxhx]

We have a formal description of this, it's called bayes theorem.

The Jordanian doctors just had poor priors.

[QuarterReptile]

In this particular case, "when you see stripes with hoofbeats, think zebra, not horse with a paintjob"