Syntax: Nor(mean, standard deviation, stream) - returns only non-negative values
This distribution is similar to the classical normal distribution, but if a negative value is generated, it is rejected and new values are generated until a non-negative value is generated. In general, this distribution will not be a good model for the time required to perform some task, since task-time distributions are almost always skewed to the right.
Syntax: Nrm(mean, standard deviation, stream) - unbounded
This is the classical normal distribution, which is found in most statistics books. It takes on real values between minus infinity and plus infinity. The density function is the familiar "bell-shaped" curve, which is symmetric about the mean. The probability that a value is between the mean minus 2 standard deviations and the mean plus two standard deviations is approximately 0.95. This distribution should not be used to model the time required to perform some task, since the normal distribution can take on negative values. Furthermore, as stated above, the distribution of the time to perform some task is almost always skewed to the right, rather than being symmetric.
Both forms require a standard deviation greater than 0.0.
Stream allows you to specify the random number stream for the distribution. There are 215 streams. Stream 1 is the default. See Seeds or Appendix D of the User's Guide for more information.