How to Create a Normal Distribution with Excel

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You might need to create randomized samples of normally distributed data for which the mean and the standard deviation of the distribution are known. This article describes how to easily create a random sample of a normal distribution with Excel.

Steps

Reviewing the Basics

Understand Normal Distributions. In the real world the values of many random variables -for example, the heights of adult males in the United States- are normally distributed. That is, the bulk of the values are around the mean of the distribution.

Know the 68 95 99.7 Rule. A normal distribution is a continuous probability distribution in which 68% of the values are within one standard deviation of the mean, 95% are within two standard deviations, and 99.7% are within three standard deviations.

Learning the Functions

Learn NORM.INV. In Excel, the NORM.INV function returns a normally distributed value given a probability, a mean, and a standard deviation. NORM refers to a normal distribution with a given mean and a given standard deviation. and INV refers to inverse, that is, finding a value given a probability, rather than finding a probability given a value.

Get to know RAND(). The RAND() function returns a random number between zero and one.

Learn to combine functions. Combining the two above-referenced functions returns a normally distributed random value with a given mean and a given standard deviation.

Creating the Sample

Entering the combined function. To create a random sample of a normal distribution with a mean of 70 and a standard distribution of 3, enter the above-referenced combined function in cell A1.