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Many quality control activities measure the yield of a process. However, measuring the yield is not a good quality characteristic. Why is that so?
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Factors
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Yield
Acceptable part
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Factor level
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A1
A2
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40
70
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A2 is better
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B1
B2
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30
90
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B2 is better
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C1
C2
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30
40
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C2 is better
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Based on the yield results above, an engineer may choose factors A2, B2 and C2 as the optimum factor levels since these levels have the higher yield levels. Putting them together, the engineer experiences a bad yield. Why?
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How do we do it?
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Our strategy is as follows:
From the results of particle size, clearly, the factors A2, B2 and C2 will result in low yield since the amount of fine particles will increase.
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Factors
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Optimum
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Factor Level
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<15
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15-50
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>50
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A1
A2
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60
0
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40
70
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0
30
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A1 is better
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B1
B2
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70
0
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30
90
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0
10
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B1 is better
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C1
C2
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60
0
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30
40
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10
60
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C1 is better
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Based on the particle size above, the engineer should identify factors that maximize the (15-50) part while minimizing <15 and >50 part.
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