
8 Six Sigma Case Studies with Minitab
®
It is evident from Figure1.5 that the proportion of defects is the sum of
the area on the left side of 19 and the area on the right side of 31. Using
Minitab
®
, the area on the left side of 19 can be calculated as 0.0000034 (see
Figure1.6).
Similarly, Minitab
®
can be used to calculate the area on the left side of 31
as shown in Figure1.7. Notice in Figure1.7 that the area on the left side of
31 is 0.999767. This means that the area on the right side of 31 is 0.000233 (i.e.,
1 – 0.999767). Hence, the proportion of defectives
= Area on the left side of 19 + Area on the right side of 31
= 0.0000034 + 0 ...