Combination Distributions
A combination distribution adds together samples from a number of individual distributions.
This can be used to create special shapes of distribution or to enable unusual circumstances to be added to normal performance.
For example a machine may usually take 5 mins (with a standard deviation of 1 minute) to perform its work but on 10% of occasions this may take an additional hour. (Use a named normal distribution in combination with a probability profile distribution that has 60 minutes for 10% and 0 minutes for 90% of its results).