Page 259 - Six Sigma Advanced Tools for Black Belts and Master Black Belts
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244 A Glossary for Design of Experiments with Examples
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3
2
1
Residuals −0.01 0 0.01 0.03 0.05 0.07 0.09 0.11 0.13 0.15
−1
−2
−3
−4
Fitted Value
Figure 16.5 Illustration of homoscedasticity.
16.4 TYPES OF FACTORIAL EXPERIMENTS
16.4.1 Crossed designs
This is the default factorial design where each factor level is independent of the re-
maining factors.
16.4.2 Nested designs
3
Consider a 2 factorial experiment. Factor A is the machinery, with line 1 and line 3
as levels. Factor B is the supplies, with levels supplier A and supplier B. Factor C
is the material, with levels regular and premium. As the regular grades for the two
suppliers are not the same, and likewise for the premium grade, factor C is said to be
0.3
0.2
Residual 0.1
0.0
−0.1
−0.2
5.5 6.0 6.5 7.0
Fitted Value
Figure 16.6 Example of a trend in residuals.
