
Quality in Production—Process Control II 367
A normal probability plot of the effects is made using Minitab
software, and the plot is shown in Figure 5�29� The dashed line was
added to the normal probability plot provided by Minitab, and it
seems to be a more plausible representation of the t than the one
drawn by Minitab� With this line we can see that the two effects
(B + ACD = 689�75) and (C + ABD = 596�25) are signicant� Assuming
that the three-factor interactions do not exist, we can conclude that
Factors B and C have the most inuence on the yield� We also notice
that a large effect is caused by the interaction