Data Analysis with Microsoft Excel: Updated for Office 2007

Chapter 12 Quality Control 501

The weight of the spray in milligrams is recorded, with two observations

taken at each of 28 times each day. Note that the data are arranged differently,

with the Time column indicating the subgroup number. The range names

have been defi ned for the workbook in Table 12-4.

Table 12-4 The Coats Workbook

Range Name Range Description

Time A2:A57 The order of the evaluation (also the subgroup number)

Weight B2:B57 The weight of the spray in milligrams

As before, you can use StatPlus to create the control chart. Note that

because n 52 (there are two observations per subgroup), A 25 1.880.

To create a control chart of the weight values:

1 Click QC Charts from the StatPlus menu and click Xbar Chart.

2 Click the Data Values button and select the Weight range name.

Click OK.

3 Click the Subgroups button and select Time from the range names

list. Click OK.

4 Click the Output button and send the control chart to a new chart

sheet named XBar Chart. Click OK twice. See Figure 12-9.

value is not within

control limits

Figure 12-9
Control chart
of weight values