Data Analysis with Microsoft Excel: Updated for Office 2007

200 Fundamentals of Statistics

To create a histogram of the random sample:

1 Click Single Variable Charts from the StatPlus menu and then click

Histograms.

2 Click the Data Values button, click the Use Range References

option button, and select the range A1:A101. Click the OK button.

3 Click the Normal curve checkbox.

4 Click the Output button and type Normal Histogram in the As a

New Chart Sheet box to send the chart to a new chart sheet. Click

the OK button.

Figure 5-14 shows the histogram of the randomly generated values

from the normal distribution

Figure 5-14

Histogram

of the 100

random

normal

values

The histogram does not follow the normal curve exactly, but as you saw

earlier, if you increase the size of the random sample, the distribution of the

sample values approaches the underlying probability distribution. A sample

size of 100 is perhaps still too small. Because you generated these values,

you already know that the data are normally distributed, but suppose you

observed these values in an experiment or study. Would the chart shown

in Figure 5-14 convince you that you’re working with normal data? It’s not

always easy to tell from a histogram whether your data are normal, so statis-

ticians have developed some procedures to check for normality.