When speaking about probability, the term random means the outcomes of an experiment have the same probability of occurring. Because of this, the outcome of the experiment produces a random sample.

Random also is commonly thought of as being synonymous with stochastic, which is from the Greek word meaning “pertaining to chance.” It is usually used to indicate a particular subject seen from the point of view of randomness. Stochastic is often thought of as the “opposite” of deterministic, a term that means random phenomena are not involved. In the case of modeling, stochastic models are based on random trials, while deterministic models always produce the same output for a given starting condition.