Design of Experiments (DOE) Flashcards
7 cards from real Certified Six Sigma Black Belt Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Design of Experiments (DOE) flashcards as text
When analyzing a DOE, a significant interaction between two factors means:
Answer: The effect of one factor depends on the level of the other factor
A significant interaction means the effect of Factor A on the response changes depending on which level of Factor B is set, so factors cannot be interpreted independently.
What is the signal-to-noise (S/N) ratio in Taguchi methods primarily used to measure?
Answer: The robustness of a product or process response to noise factors
Taguchi's S/N ratio quantifies how much variation (noise) exists relative to the mean signal, with higher S/N indicating more robust performance.
In a 2^(4-1) fractional factorial experiment, how many runs are required?
Answer: 8
A 2^(4-1) design is a half-fraction of a full 2^4 = 16 run design, so it requires 2^(4-1) = 2^3 = 8 runs.
Which DOE term describes the difference in response between the high and low levels of a factor, averaged across all other factor combinations?
Answer: Main effect
The main effect of a factor is the average change in response when moving from the low level to the high level, averaged over all levels of other factors.
A normal probability plot of effects in a factorial experiment is used to:
Answer: Identify which effects are statistically significant versus noise
On a normal probability plot, insignificant effects fall on a straight line (noise), while significant effects deviate noticeably from the line.
What is the purpose of blocking in a designed experiment?
Answer: To reduce the effect of a known nuisance variable on the comparison of treatments
Blocking groups experimental runs by a known nuisance variable (e.g., batches, days, machines) so its effect can be removed from the error term.
In response surface methodology, a Box-Behnken design differs from a Central Composite Design primarily because it:
Answer: Does not include corner points of the factor space
Box-Behnken designs avoid the extreme corner combinations of all factors at their highest or lowest levels simultaneously, which can be impractical or dangerous.