Certified Six Sigma Black Belt Exam Design of Experiments (DOE) 2

Question 1

In a 2^k factorial design, what does the 'k' represent?

Accepted Answer

The number of factors

Answer

In a 2^k factorial design, k is the number of factors and 2 represents the number of levels (high and low) for each factor.

Question 2

Which type of DOE design is most appropriate when the experimenter suspects curvature in the response surface?

Accepted Answer

Central Composite Design (CCD)

Answer

Central Composite Design (CCD) includes axial (star) points that allow estimation of quadratic effects and detection of curvature.

Question 3

What is the primary purpose of randomization in a designed experiment?

Accepted Answer

To guard against lurking variables and time-related effects

Answer

Randomization distributes the effects of unknown nuisance variables across all experimental runs, preventing systematic bias.

Question 4

In a fractional factorial design, a resolution III design means:

Accepted Answer

Main effects are confounded with 2-factor interactions

Answer

In a resolution III design, main effects are aliased (confounded) with 2-factor interactions, so they cannot be separately estimated.

Question 5

A Plackett-Burman design is best used for:

Accepted Answer

Screening many factors to identify the vital few

Answer

Plackett-Burman designs are highly efficient screening designs that study many factors in relatively few runs to identify significant main effects.

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