Microsoft Office Tutorials and References

In Depth Information

Working with Normal Distributions

In statistics, a common topic is the normal distribution, also known as a
bell curve.
Excel has several functions

designed to work with normal distributions. This is not a statistics book, so I assume that if you're reading this

section, you're familiar with the concept.

The examples in this section are available at this book's website. The filename is nor-

mal distribution.xlsx.

Figure 10-6 shows a workbook that contains formulas that generate the two charts: a normal distribution and a

cumulative normal distribution. The formulas use the values entered into cell B1 (name
Mean
) and cell B2

(named
SD
, for
standard deviation
). The values calculated cover the mean plus/minus three standard deviations.

Column A contains formulas that generate 25 equally spaced intervals, ranging from –3 standard deviations to

+3 standard deviations.

A normal distribution with a mean of 0 and a standard deviation of 1 is known as the “standard normal distribu-

tion.” The worksheet is set up to work with any mean and any standard deviation.

Formulas in column B calculate the height of the normal curve for each of the 25 values in column A. Cell B5

contains this formula, which is copied down the column:

=NORM.DIST(A5,Mean,SD,FALSE)