Certified Six Sigma Black Belt Exam Certified Six Sigma Black Belt Design of Experiments (DOE) Questions and Answers 3

Question 1

What is the defining relation used to determine the alias structure of a fractional factorial design?

Accepted Answer

The set of generators and their generalized interactions that equal the identity column

Answer

The list of all main effects included in the experiment

Answer

The ANOVA table showing significant factors

Answer

The blocking scheme selected by the experimenter

Question 2

In a Plackett-Burman design with 12 runs, what is the maximum number of factors that can be studied?

Accepted Answer

11

Answer

12

Answer

10

Answer

6

Question 3

A team uses a central composite design (CCD) and finds significant lack of fit. What is the most appropriate next step?

Accepted Answer

Consider adding higher-order terms or transforming the response variable

Answer

Immediately adopt the current model for production

Answer

Remove all center point runs and reanalyze

Answer

Switch to a screening design with more factors

Question 4

Which principle ensures that the effect of an uncontrolled nuisance variable is spread evenly across all treatment combinations in a DOE?

Accepted Answer

Randomization

Answer

Replication

Answer

Blocking

Answer

Confounding

Question 5

In a split-plot experiment, why are some factors called 'hard-to-change'?

Accepted Answer

Resetting them for every run is impractical or very costly

Answer

They have more levels than other factors

Answer

Their effects are always insignificant

Answer

They must be tested at the center point only

Question 6

What does the term 'rotatability' mean in the context of a response surface design?

Accepted Answer

The prediction variance is the same at all points equidistant from the design center

Answer

All factors have the same number of levels

Answer

The design can be rotated into a blocking structure

Answer

Main effects are orthogonal to interaction effects