The MathResource
empirical probability,
n. (Statistics) the posterior probability of an event derived on the basis of its observed frequency in a sample. For example, suppose we have obtained 52 heads in 100 tosses of coin A and 43 heads in 100 tosses of coin B; if we now toss one of these coins without knowing which and the outcome is tails, then, by Bayes's theorem, the empirical probability that it is coin B is approximately 54.3%. Compare mathematical probability.