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September 26, 2005

Normal Distribution III

In previous tips, we showed how to generate random input data that was distributed according to our requirements. In particular, we looked at the Normal Distribution here and here

There is an even easier way to generate our normally distributed data - and that is to use the NORMINV function. NORMINV returns the inverse of the normal cumulative distribution. Given a cumulative probability, a mean, and a standard deviation, NORMINV returns the value that cuts off the cumulative probability. The arguments to the function are :

NORMINV(number, mean, stdev) where

• number represents the probability value used to determine the inverse normal distribution.
• mean represents the mean value in the normal distribution.
• stdev represents the standard deviation of the normal distribution.

By using the RAND function with multiple calls to NORMINV, we can obtain a nrmally distributed input data set.

In the example below, we set the mean to 0.0 and the stdev to 1.0. As you can see, the generated data set comes pretty close to our requirements.



Next, we will plot a frequency graph of our data.

Posted by Dave at September 26, 2005 08:13 PM

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