ABSTRACT
The Normal distribution is a continuous distribution completely specified by two parameters: its Expected Value and its Standard Deviation. The Poisson distribution for a stochastic process is completely specified by one parameter: its Expected Value λ. Unlike the continuous Normal distribution, the Poisson distribution is discrete and takes on only integer values zero or larger. The difference between the actual customer demand data points and the forecasted customer demand data points is the unexplained deviation in the data. If all the actual customer demand data points were to lie exactly on the forecasted line, the unexplained deviation would be zero.
