Process Capability Analysis 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 Process Capability Analysis flashcards as text
Which prerequisite must be verified BEFORE conducting a process capability analysis?
Answer: The process must be in statistical control
Process capability analysis is only meaningful when the process is in statistical control, ensuring that variation is random, stable, and predictable over time.
What does DPMO stand for in the context of Six Sigma process capability?
Answer: Defects Per Million Opportunities
DPMO (Defects Per Million Opportunities) normalizes defect rates to one million opportunities, enabling comparison across processes with different complexities.
How many DPMO does a true Six Sigma process produce when accounting for the standard 1.5 sigma long-term shift?
Answer: 3.4
With the 1.5 sigma long-term drift applied, a six sigma process produces 3.4 DPMO — the defining benchmark of Six Sigma quality.
Which graphical tool is most appropriate for verifying the normality assumption before performing standard capability analysis?
Answer: Normal probability plot
A normal probability plot (or Anderson-Darling test) graphically assesses whether data follows a normal distribution, which is required for valid Cp and Cpk calculations.
What happens to the Cpk value when the process mean shifts closer to a specification limit?
Answer: Cpk decreases because the distance to the nearest limit shrinks
Cpk uses the minimum distance from the mean to either specification limit; as the mean shifts toward a limit, that minimum distance shrinks, reducing Cpk.
Which capability approach is most appropriate when process data follows a non-normal distribution?
Answer: Use percentile-based or distribution-specific capability indices
Percentile-based capability indices use actual data percentiles to define process boundaries, avoiding the invalid normality assumption for skewed or non-normal distributions.
The Taguchi Capability Index (Cpm) differs from Cpk primarily because it:
Answer: Penalizes deviation of the process mean from the target value T
Cpm incorporates a target value T in its denominator, penalizing the process whenever the mean deviates from the target — even when still within specification.