The following summary can be used as a guide to the selection of an appropriate probability distribution:
◼ If a variable is a discrete variable, the Poisson or Binomial distribution may be applied to model an either/or outcome.
◼ If the distribution of the variable is symmetric and continuous, the normal distribution should be used; if it is symmetric but bounded, the symmetric triangular or truncated normal distribution may be applied.
◼ If the distribution is asymmetric but bounded, the triangular distribution may be used, either left or right tailed.
◼ If there is no information as to the likely form of the distribution, it should be assumed that all variables have an equal probability of occurrence and the uniform distribution should be used.