what is Bayes Theorem, anyway?
Bayes’ Theorem provides a way to apply quantitative reasoning to what we normally think of as “the scientific method”. When several alternative hypotheses are competing for our belief, we test them by deducing consequences of each one, then conducting experimental tests to observe whether or not those consequences actually occur. If an hypothesis predicts that something should occur, and that thing does occur, it strengthens our belief in the truthfulness of the hypothesis. Conversely, an observation that contradicts the prediction would weaken (or destroy) our confidence in the hypothesis. In many situations, the predictions involve probabilities– one hypothesis might predict that a certain outcome has a 30% chance of occurring, while a competing hypothesis might predict a 50% chance of the same outcome. In these situations, the occurrence or non-occurrence of the outcome would shift our relative degree of believe from one hypothesis toward another. Bayes theorem provides a way to ca
