### Definition(s)

#### Bayesian Probability

The process of evaluating the probability of a hypothesis through 1) the specification of a prior probability and 2) modification of the prior probability by incorporation of observed information to create an updated posterior probability.

**Sample Usage: **The analyst applied Bayesian probability techniques to incorporate new evidence and update her estimate of the threat probability.

**Annotation: **This concept is also referred to as Bayesian probabilistic inference. Bayesian probability evaluates likelihoods as probabilities rather than frequencies.

*Source: DHS Risk Lexicon, U.S. Department of Homeland Security, 2010 Edition. September 2010 Regulatory Guidance*