Data Analysis with Microsoft Excel: Updated for Office 2007

Chapter 6 Statistical Inference 249

The observed difference values don’t appear to follow the normal curve

particularly well. Let’s see whether the normal probability plot provides

more information.

To create a normal probability plot of the difference data:

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

Normal P-plots.

2 Click the Data Values button and select Diff from the list of range

names in the workbook.

3 Click the Output button and save your chart to the P-Plot chart

sheet.

4 Click the OK button twice to create the normal probability plot. See

Figure 6-15.

Figure 6-14
Histogram of the
difference data