The long-term frequency of an event relative to all alternative events, and usually expressed as a decimal fraction. Probabilities range between zero (if the event never occurs) and 1 (if the event always occurs and no alternative event ever occurs). In some cases we know a probability a priori, as in the case of a coin toss. In the long run, the coin will come up tails with a frequency of ˙5. More often, a probability must be estimated by averaging the results of many trials. See conditional probability, independent probabilities, significance of results.
Subjects: Genetics and Genomics.