Statistical Thinking and Variation Flashcards
7 cards from real Lean Six Sigma Yellow Belt Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Statistical Thinking and Variation flashcards as text
What does DPMO stand for in Six Sigma quality measurement?
Answer: Defects per Million Opportunities
DPMO (Defects per Million Opportunities) is the standard Six Sigma metric for measuring quality, normalizing defect counts so processes of different scales can be compared.
A process operating at Six Sigma quality produces approximately how many defects per million opportunities?
Answer: 3.4 defects per million opportunities
Six Sigma quality is defined as approximately 3.4 DPMO, accounting for a 1.5-sigma long-term shift in the process mean from the centered target.
The 'sigma level' of a process measures:
Answer: How many standard deviations fit between the process mean and the nearest specification limit
The sigma level indicates how capable a process is by measuring how many standard deviations fit between the process mean and the nearest specification limit — higher is better.
Overadjusting a stable process that exhibits only common cause variation will:
Answer: Increase variation and worsen process performance
Tampering with a stable process — reacting to common cause variation as if it were a special cause — actually adds variation and worsens performance, a phenomenon Deming called 'tampering.'
Process capability analysis compares:
Answer: The natural process spread to the customer specification width
Process capability compares the natural variation of the process (spread) to the customer's specification range to determine whether the process can reliably meet requirements.
Which of the following best explains why reducing variation is central to Six Sigma?
Answer: Reduced variation makes processes more predictable and consistently meets customer requirements
Reducing variation makes process outputs more consistent and predictable, which directly improves quality and increases the likelihood of meeting customer specifications every time.
In the context of statistical thinking, which statement about variation is correct?
Answer: Variation exists in every process and understanding its type guides the correct response
Statistical thinking holds that variation is present in all processes and that correctly identifying its type — common or special cause — determines whether to improve the system or investigate a specific event.