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Six Sigma Green Belt· Exam reference card · 2026 · Edureify AI
Six Sigma Green Belt

Six Sigma Green Belt Cheat Sheet

Six Sigma Green Belt Tests DMAIC Application, Not Statistical Theory in Isolation

Every Six Sigma question is a process improvement scenario. Know which DMAIC phase you're in and which statistical tool applies to that phase.

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Among the harder certs
Avg: Approximately 63–68%
Pass: 750 / 1000
Most candidates understand Six Sigma Green Belt concepts — and still fail. This exam tests how you apply knowledge under pressure.
Core Framework

DMAIC Framework: Phase-Tool Mapping

Six Sigma Green Belt (SSGB) tests DMAIC methodology and statistical tools within the correct phase. Questions present scenarios — you must identify the phase and apply the appropriate tool. Applying the right tool in the wrong phase is a systematic error.

  1. 01
    Define — Project charter, SIPOC, VOC, CTQs, stakeholder analysis
  2. 02
    Measure — Process maps, MSA (measurement system analysis), baseline capability (Cp, Cpk)
  3. 03
    Analyze — Root cause analysis, fishbone, 5 Whys, regression, hypothesis testing
  4. 04
    Improve — DOE (design of experiments), solution implementation, pilot testing
  5. 05
    Control — Control charts, SPC, control plan, process documentation, handover
Scenario Traps

Wrong instinct vs correct approach

A process has a Cpk of 0.8 and the team wants to improve capability
✕ Wrong instinct

Reduce variation to improve the Cp

✓ Correct approach

Cpk of 0.8 means the process is both inadequately centered AND may have excessive variation — address centering first (shift the mean toward the target), then reduce variation; Cp alone doesn't address centering

A control chart shows a point outside the control limits
✕ Wrong instinct

Adjust the process to bring the point back within limits

✓ Correct approach

A point outside control limits indicates special cause variation — stop the process, investigate the specific cause of that point, identify and eliminate the root cause before continuing; don't adjust the process without understanding why

The team is selecting a solution during the Improve phase
✕ Wrong instinct

Select the solution with the most stakeholder support

✓ Correct approach

Use a solution selection matrix or Pugh matrix to score solutions against CTQs (Critical to Quality requirements), cost, feasibility, and risk — data-driven selection, not political selection

Quick Rules

Know these cold

  • ▸ DMAIC phases are sequential — don't skip or reorder them
  • ▸ Root cause analysis belongs in Analyze — don't solve problems before finding causes
  • ▸ Cpk accounts for both spread and centering; Cp accounts for spread only
  • ▸ Control charts detect special cause variation — investigate before adjusting
  • ▸ 3.4 DPMO = Six Sigma level (with the 1.5 sigma shift convention)
  • ▸ VOC → CTQs → metrics → this translation chain must be explicit in the Define phase
  • ▸ Measurement System Analysis (MSA) must confirm measurement reliability before collecting baseline data
Self Check

Can you answer these without checking your notes?

In this scenario: "A process has a Cpk of 0.8 and the team wants to improve capability" — what should you do first?
Cpk of 0.8 means the process is both inadequately centered AND may have excessive variation — address centering first (shift the mean toward the target), then reduce variation; Cp alone doesn't address centering
In this scenario: "A control chart shows a point outside the control limits" — what should you do first?
A point outside control limits indicates special cause variation — stop the process, investigate the specific cause of that point, identify and eliminate the root cause before continuing; don't adjust the process without understanding why
In this scenario: "The team is selecting a solution during the Improve phase" — what should you do first?
Use a solution selection matrix or Pugh matrix to score solutions against CTQs (Critical to Quality requirements), cost, feasibility, and risk — data-driven selection, not political selection
Failure Patterns

Common Exam Mistakes — What candidates get wrong

Applying statistical tools in the wrong DMAIC phase

Root cause analysis belongs in Analyze, not Measure. Control charts belong in Control, not Improve. Statistical process control is for sustaining improvements, not finding root causes. Phase-tool mapping must be precise.

Confusing Cp and Cpk

Cp measures process capability relative to specification width (spread only). Cpk measures process capability while accounting for process centering. A process can have a high Cp (adequate spread) but low Cpk (poorly centered). Candidates use Cp when Cpk is required for centered capability questions.

Misidentifying when to use hypothesis testing

Hypothesis testing is used in the Analyze phase to confirm whether observed differences between groups are statistically significant. Candidates apply it in Measure (for baseline) or Improve (for solution selection) where it doesn't belong.

Treating variation as always random

Special cause variation is assignable to specific events and must be investigated and eliminated. Common cause variation is inherent to the process and reduced through process redesign. Applying control charts to special cause variation without investigation is a fundamental Six Sigma error.

Confusing DPMO and process sigma level

DPMO (Defects Per Million Opportunities) and sigma level have a specific relationship — 3.4 DPMO = 6 Sigma. Candidates mix up the direction of the relationship or misapply the 1.5 sigma shift convention.

Six Sigma Green Belt tests statistical application in context. Test whether you're using the right tool in the right phase.

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