Six Sigma Green Belt practice questions and exam guide

What does a SIPOC diagram represent?

1. Cost analysis
2. Time tracking
3. Risk analysis
4. Suppliers, Inputs, Process, Outputs, Customers — high-level process map identifying scope and key components
5. Sales process only

Answer: D — Suppliers, Inputs, Process, Outputs, Customers — high-level process map identifying scope and key components

SIPOC: Define-phase tool. High-level process overview. Maps boundaries, key relationships. Used to align team on scope. Compare process maps (more detailed) and value-stream maps (lean-focused with metrics).

A data collection plan should specify:

1. Only the metric name
2. Only the data owner
3. Only the sample size
4. What, who, when, where, how, and the operational definition

Answer: D — What, who, when, where, how, and the operational definition

Robust data plan = full 5W+H + op def. A, B, C are individually insufficient.

5S workplace organization stands for:

1. Random words
2. Random Japanese
3. Just clean
4. One step
5. Sort (Seiri), Set in order (Seiton), Shine (Seiso), Standardize (Seiketsu), Sustain (Shitsuke) — visual workplace foundation of Lean

Answer: E — Sort (Seiri), Set in order (Seiton), Shine (Seiso), Standardize (Seiketsu), Sustain (Shitsuke) — visual workplace foundation of Lean

5S: Japanese workplace org method. Foundation for Lean. Sort: remove unneeded. Set in order: place for everything. Shine: clean, inspect. Standardize: maintain consistency. Sustain: discipline. Some add 6th S: Safety. Visual workplace techniques.

Which is the best definition of a process's 'sigma level'?

1. The standard deviation of the process output
2. The number of opportunities per unit
3. The number of standard deviations between the process mean and the nearest specification limit
4. The mean of three sigma samples

Answer: C — The number of standard deviations between the process mean and the nearest specification limit

Sigma level = Z = (nearest spec − mean)/σ. A confuses the level with σ itself. B is opportunities count. D is nonsense — common misconception traps.

MEASURE phase deliverables:

1. Solutions
2. Just root cause
3. Detailed process map, data collection plan, baseline performance (process capability, sigma level, defect rates), measurement system analysis (MSA) showing data is reliable
4. Pure analysis
5. Customer survey

Answer: C — Detailed process map, data collection plan, baseline performance (process capability, sigma level, defect rates), measurement system analysis (MSA) showing data is reliable

Measure phase: quantify current state. Output: validated baseline metrics. Includes: detailed process map, operational definitions, data collection plan, baseline data, MSA (R&R study), process capability indices (Cp, Cpk, Pp, Ppk). Foundation for analysis.

When should a team use DMADV instead of DMAIC?

1. When improving any existing process
2. When the existing process is too costly to measure
3. When designing a new product or process, or when an existing process needs fundamental redesign rather than incremental improvement
4. When the Champion is unavailable

Answer: C — When designing a new product or process, or when an existing process needs fundamental redesign rather than incremental improvement

DMADV (Design for Six Sigma) is for new designs or fundamental redesigns where DMAIC's incremental improvement won't close the gap. A and B are the trap — DMAIC handles existing-process improvement.

Pearson correlation coefficient r = -0.85 indicates:

1. Strong negative linear relationship between two continuous variables
2. Weak correlation
3. Causation between the two variables
4. No relationship

Answer: A — Strong negative linear relationship between two continuous variables

|r| close to 1 = strong; sign = direction. C confuses correlation with causation (classic misconception).

Cp = 1.0 means:

1. Process is centered perfectly
2. Process spread exactly equals the spec width (tolerance = 6σ); process is barely capable, no margin for shift
3. Process is incapable
4. Process has zero variation

Answer: B — Process spread exactly equals the spec width (tolerance = 6σ); process is barely capable, no margin for shift

Cp = (USL−LSL)/(6σ) = 1.0 means spread fills spec. A is Cp vs Cpk confusion. C is misread. D is wrong.

Which statistical test compares means of two groups?

1. Chi-square
2. Regression
3. ANOVA (used for 3+ groups)
4. t-test (two-sample t-test for independent groups; paired t-test for matched pairs)
5. Correlation

Answer: D — t-test (two-sample t-test for independent groups; paired t-test for matched pairs)

Hypothesis testing: t-test compares 2 means (independent or paired). ANOVA compares 3+ means. Chi-square tests categorical associations. Six Sigma uses these in Analyze phase. Alpha (α) typically 0.05.

A Yellow Belt argues Six Sigma applies only to manufacturing. The best counter is:

1. Six Sigma was actually invented for healthcare
2. Manufacturing applications no longer use Six Sigma
3. Six Sigma applies to manufacturing only — the Yellow Belt is correct
4. Six Sigma originated at Motorola but has been successfully applied in healthcare, finance, IT, and services — DMAIC is process-agnostic

Answer: D — Six Sigma originated at Motorola but has been successfully applied in healthcare, finance, IT, and services — DMAIC is process-agnostic

Common misconception. Six Sigma is process-agnostic. A is historically wrong (Motorola, 1986). C capitulates to the misconception.

Which is the highest-level process visualization?

1. Detailed flowchart with decision diamonds
2. Swim-lane diagram with cross-functional handoffs
3. SIPOC
4. Value stream map with cycle time data

Answer: C — SIPOC

Detail order: SIPOC (highest) < flowchart < swim-lane < VSM. Off-by-one process-map detail trap.

A team wants to compare mean cycle times across 4 shifts. The appropriate test is:

1. Two-sample t-test
2. Chi-square test
3. Pearson correlation
4. One-way ANOVA

Answer: D — One-way ANOVA

ANOVA = means across 3+ groups. A is for 2 groups. B is categorical association. C is linear relationship strength. Classic test-selection trap.

DOE (Design of Experiments)?

Systematic method to determine relationship between input factors and output. Statistical experiments.

ADKAR model?

Awareness, Desire, Knowledge, Ability, Reinforcement. Stages of individual change.

When use ANOVA?

Compare means of 3+ groups.

Range?

Max - Min.

Control chart?

Plot data over time. Shows whether process is in control.

Alternative hypothesis (Ha)?

There IS a difference / effect.