
262 Six Sigma Case Studies with Minitab
®
Notice above that, degrees of freedom = (rows – 1) * (columns – 1) = (2 – 1) *
(2 – 1) = 1.
In order to view the above on a chi-square probability distribution plot,
select “Probability Distribution Plot” as shown in Figure 15.7. Doing so
opens the dialog box shown in Figure 15.8. Select “View Probability” as
shown and click on “OK”. It opens the dialog box shown in Figure15.9. Select
“Chi-Square” from the drop-down menu for “Distribution” and enter “1” for
“Degrees of freedom”. Click on “OK” and it opens the dialog box shown in
FIGURE 15.7
Selection of “Probability Distribution Plot” for suppliers.