One interesting point that has served me well over the years came originally from Dr. Gene Coffman, operations research specialist at Ford. He argued strongly that the normal distribution is almost NEVER an appropriate distribution to use in a simulation (e.g., for a cycle time, time to next breakdown, time to repair, time to next arrival....). In practice, the distribution used for these situations should typically be positive (right) skewed, not symmetric. Also, the normal distribution is not bounded below, whereas all these situations are surely bounded below by zero.
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E. Williams, PMC
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