Data Analysis with Microsoft Excel: Updated for Office 2007

196 Fundamentals of Statistics

Because normally distributed data appear so often in statistical studies,

these benchmarks are an important rule of thumb. For example, if you are

trying to calculate a range that will incorporate most of the data, taking the

mean 6 2 standard deviations is a fast way of estimating that range.

Excel Worksheet Functions

Excel includes several functions to work with the normal distribution

described in Table 5-1.

Table 5-1 Functions with the Normal Distribution

Function Description
NORMDIST(y, mean, std_dev, type) Uses the normal distribution with m 5 mean and
s 5 std_dev. Setting type 5 TRUE calculates
the probability of Y # y. Setting type 5 FALSE
calculates the value of the probability density
function at y.
NORMINV(p, mean, std_dev) Returns the value y from the normal distribution for
m 5 mean and s 5 std_dev, such that p(Y # y) 5 p.

Figure 5-11

Probabilities

under the

normal

curve

number of

standard deviations

away from

the mean

(continued)