
124 Six Sigma Case Studies with Minitab
®
8.3 Analyze Phase
Select “Item Analysis” as shown in Figure8.8. Doing so opens the dialog box
shown in Figure8.9. Then, select “Q1 Q2P Q3P Q4 Q5 Q6P Q7” columns for
“Variables”. Click on “Graphs” and the dialog box shown in Figure8.10 opens.
Check the box for “Matrix plot for data with smoother” if it is not already
checked, and click on “OK”. This takes you back to the dialog box shown in
Figure8.9. Click on “OK” and the outputs shown in Figures8.11 and 8.12 are the
results. Figure8.11 is a matrix plot for all possible pairs of questions. It shows
for each pair, how, with an increase in the rati ...