The conditional probability of a measurement given a hypothetical state of the world (or typically some specific parameters of the world). For example, the probability that six tosses of a coin will come out heads given the coin is fair is 1/64, so if this result occurs, the likelihood that the coin is fair is 1/64. This likelihood is used in slightly different ways by traditional statistics and Bayesian statistics to work back from the measurement to assess its evidence for or against the value of the underlying property or state of the world.
Defined on pages 58, 58
Used on pages 57, 58, 59, 60, 61, 62, 65, 71, 72, 74, 77, 80, 81, 92, 93