Bayesian Cats: Updating My Priors

Dinner o’clock?

Bayes’ rule updates a belief in light of evidence:

$P(H \mid E) = \frac{P(E \mid H)\, P(H)}{P(E)}$

Our cat’s prior that it’s dinner time is low at 3pm — but the sound of a can opener is strong evidence, so the posterior spikes.

The takeaway

You already reason like this; Bayes just writes it down.