Base Rate Calculator

The base rate is the underlying probability of an event in a population before any new evidence is considered. For example, the prevalence of a disease in a population.

The base rate fallacy is the tendency to ignore the base rate (prior probability) when evaluating new evidence, leading to incorrect conclusions about conditional probabilities.

Use Bayes' theorem: P(disease | positive) = (P(positive | disease) * P(disease)) / P(positive). Our calculator helps you compute this from raw counts.

Yes, as long as you can express the problem as a mathematical expression involving counts or probabilities. The calculator evaluates standard arithmetic expressions.