Some problems in risk analysis cannot be expressed in an analytical form; others are difficult to define in a deterministic manner. Monte Carlo methods (also known as stochastic simulation techniques) consist of running "numerical experiments" to observe what happens over a large number of runs of a stochastic model. They consist of using repeated random sampling from input probability distributions, execution of the model with these stochastic inputs, then aggregation of the large number of executions to obtain an estimate of the quantity of interest. These methods rely on the ability of computers to generate pseudo-random numbers from various relevant probability distributions.
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