Data Analysis with Microsoft Excel: Updated for Office 2007

414 Statistical Methods

Graphing the Data to Verify Assumptions

Before performing a two-way analysis of variance on the data, you should

plot the data values to see whether there are any major violations of the as-

sumptions of equal variability in the different cells. Note that you can use

the Cola_Type variable to identify the eight cells.

To create multiple histograms of the foam data:

1 Click Multi-variable Charts from the StatPlus menu and then click

Multiple Histograms.

2 Click the Data Values button, select Foam from the range names list,

and click OK.

3 Click the Categories button, select Cola_Type from the range names

list, and click OK.

4 Click the Display normal curve checkbox.

5 Click the Output button, send the charts to a new worksheet named

Histograms, and click OK.

6 Click OK to generate the histograms shown in Figure 10-16.

Figure 10-15
Cola workbook