Six Sigma Green Belt Flashcards

A Green Belt wants to test whether there is a significant difference in mean cycle times between three machine types. Which statistical test is most appropriate?

Answer: One-way ANOVA

One-way ANOVA compares means across three or more groups simultaneously, making it appropriate for comparing cycle times among three machine types.

What is the purpose of a process capability index (Ppk) as distinct from Cpk?

Answer: Ppk uses overall process variation while Cpk uses within-subgroup short-term variation

Ppk uses total (long-term) standard deviation including all sources of variation, while Cpk uses within-subgroup (short-term) variation representing process entitlement.

In a control chart, what does an 'out-of-control' signal indicate?

Answer: A special cause of variation is likely present

An out-of-control signal on a control chart indicates a statistically unusual pattern suggesting a special (assignable) cause of variation is present.

Which lean tool is used to visually map the flow of materials and information to identify waste and non-value-added activities?

Answer: Value Stream Mapping (VSM)

Value Stream Mapping creates a visual representation of the entire process flow, highlighting waste, delays, and non-value-added steps that are candidates for elimination.

A team applies the 5 Whys technique. What is the main risk of this analysis method?

Answer: It can lead to different root causes depending on who is asking the questions

The 5 Whys is vulnerable to subjective bias since different teams may trace different causal chains from the same symptom, potentially reaching different root causes.

What does 'measurement system bias' mean in the context of a Gage R&R study?

Answer: The measurement system consistently reads higher or lower than the true value

Bias is a systematic offset between the measurement system's average reading and the true reference value, indicating a calibration issue.

In the Control phase, which document defines the actions to take if a process goes out of control?

Answer: Control plan

The control plan specifies monitoring methods, control limits, response plans, and responsible parties for sustaining process improvements.