Six Sigma Basics is one of the core study topics in our Business catalog. This page gathers the essentials: what the topic covers, the key concepts and
terminology, worked examples and exam-style questions — everything also available as 215 companion flashcards for spaced-repetition practice.
Main questions this page answers:
- What does DMAIC stand for in Six Sigma?
- Which Six Sigma belt level is responsible for leading project teams?
- What is the purpose of a Fishbone diagram in the Analyze phase?
- What does a p-chart monitor?
- Define process capability index Cp.
- What is Cpk and how does it differ from Cp?
- Name the seven classic types of muda (waste) in lean.
- What is the Voice of Customer (VOC)?
What does DMAIC stand for in Six Sigma?
Define, Measure, Analyze, Improve, Control. It is the data-driven improvement cycle used for projects aimed at improving existing processes.
What is the difference between an Xbar-R and Xbar-S chart?
Xbar-R uses subgroup ranges and is preferred when subgroup size n ≤ 10. Xbar-S uses subgroup standard deviations and is more accurate when n > 10.
What is the difference between Cp and Cpk?
Cp measures potential process capability assuming the process is centered on specification. Cpk measures actual capability,
accounting for any shift of the mean toward one specification limit.
What is a stakeholder analysis in the Define phase?
Stakeholder analysis identifies all parties affected by the project, their interests, influence, and communication needs. It ensures engagement and prevents resistance during execution.
What is a Type II error in hypothesis testing?
A Type II error (beta) occurs when failing to reject a false null hypothesis. It represents missing a real effect. Statistical power (1-β) is the probability of correctly rejecting a false null hypothesis.
What is a cost-benefit analysis in the improve phase?
Cost-benefit analysis quantifies expected savings (defect reduction, cycle time improvement) versus implementation costs (training, equipment, software). A positive ROI justifies proceeding with the selected solution.
What is a Z-score in Six Sigma?
A Z-score expresses how many standard deviations a data point lies from the mean. Higher Z-scores indicate better process performance; Six Sigma quality corresponds to a Z of 6.
What is a Standard Operating Procedure?
An SOP is a documented step-by-step set of instructions for routine tasks. SOPs are common outputs of the Control phase to sustain improvements and standardize new processes.
What is a benchmark in Six Sigma project selection?
A reference point—internal, competitive, or industry best—used to set realistic improvement goals and justify project scope.
What is the difference between population and sample in statistics?
A population includes all items of interest; a sample is a subset drawn from the population used to estimate population parameters due to practical constraints.