Prepare for the ASQ Certified Six Sigma Green Belt (CSSGB) exam by connecting tools to the decisions they support. Use the six-domain map, calculate the before-and-after rates, and distinguish a descriptive change from a supported explanation of its cause.
Who qualifies, and which outline should you use?
CSSGB requires three years of relevant full-time paid work experience. ASQ grants no educational waivers for this certification. The current linked Body of Knowledge is the 2022 version.
A degree or preparation course does not replace the experience requirement. Compare your actual work with the areas in the outline before applying. CSSGB does not use the Black Belt project-affidavit requirement.
DMAIC means Define, Measure, Analyze, Improve and Control. The exam also covers an overview of Six Sigma and the organization, so preparation should include all six areas below.
Sources: The ASQ Certified Six Sigma Green Belt certification brochure and Body of Knowledge (2022 BoK) — cssgb-cert-insert.pdf; Six Sigma Green Belt Certification (CSSGB) — ASQ certification page — Requirements, Examination, Policies and Procedures, Application Process, Testing Dates
What should you review in the six domains?
The official domain allocation totals 100 scored questions. Use the full outline for the individual tasks and cognitive levels.
The counts indicate exam emphasis; they are not percentages of all 110 computer-based items or mandatory allocations of study time. Adjust your review to the gaps you find.
| Domain | Scored questions | A useful review task |
|---|---|---|
| I. Overview: Six Sigma and the Organization | 11 | Review organizational drivers, Lean concepts and the listed design roadmaps. |
| II. Define Phase | 20 | Develop a measurable problem statement, scope and customer requirements. |
| III. Measure Phase | 20 | Review operational definitions, measurement systems, data and capability topics. |
| IV. Analyze Phase | 18 | Match statistical questions to data, groups, assumptions and analysis tools. |
| V. Improve Phase | 16 | Review improvement methods and how proposed changes will be evaluated. |
| VI. Control Phase | 15 | Review control plans, statistical process control and sustaining changes. |
Practise comparing before-and-after defect rates
Compare proportions using each period’s own denominator. Then calculate percentage-point change and relative change separately.
This original exercise is descriptive. Its fictional target is supplied by the scenario, and no statistical-test or sampling-design assumptions are added.
Practice example
For this fictional exercise, the same operational definition of a defective unit and consistent inspection are used in both periods. Before a change, 30 of 200 inspected units are defective. After the change, 24 of 240 inspected units are defective. Each unit is counted once. The internal target is a defective-unit rate of 12% or lower. Calculate both rates, the decline in percentage points and the relative decrease. Does the after-sample meet the target, and what do these counts alone not establish?
Show answer
Before: 30/200 = 15%. After: 24/240 = 10%. The decline is 15% - 10% = 5 percentage points. Relative to the original rate, the decrease is (15% - 10%)/15% = 1/3, or about 33.3%. The after-sample’s 10% meets the stated target of 12% or lower.
The two denominators differ, so the raw counts alone do not describe the size of the rate change. A five-percentage-point decline is not a five-percent relative decline. The counts do not establish causation, statistical significance or stable long-run performance. Statistical inference would require a justified model and sampling assumptions; a lower observed proportion by itself does not supply those assumptions.
What is the difference between stability and capability?
NIST defines process capability by comparing the output of an in-control process with specification limits. A favorable-looking capability number alone does not establish that the process is stable.
For study, identify which evidence addresses behavior over time and which addresses the stated specifications. NIST’s Cp and Cpk treatment assumes a normal population, and estimates need suitable data. Avoid interpreting an arbitrary index as proof that every unit meets requirements.
The two proportions in the exercise supply a before-and-after description. They do not provide a time-ordered control-chart study or establish the population assumptions needed for a capability analysis.
Sources: The ASQ Certified Six Sigma Green Belt certification brochure and Body of Knowledge (2022 BoK) — cssgb-cert-insert.pdf; 6.1.6. What is Process Capability? — https://www.itl.nist.gov/div898/handbook/pmc/section1/pmc16.htm
How can you turn practice errors into a study plan?
Map each missed or guessed answer to the current Body of Knowledge task. Identify whether you need to revisit the concept, calculation, evidence or reference lookup.
Choose preparation materials by their coverage of the current outline. Compare an existing book’s contents with that outline before deciding what needs supplementing. Adapt your study time to the gaps you find rather than adopting a fixed preparation period.
- For each calculation, write the numerator, denominator, units and assumptions before using a formula.
- For test-selection review, identify the parameter, data type, groups and pairing; then check the method’s assumptions.
- For measurement-system topics, distinguish measured values from classification judgments and review the relevant tools.
- After a practice set, return to the full map so familiar calculation questions do not crowd out Define, Improve or Control.
Sources: The ASQ Certified Six Sigma Green Belt certification brochure and Body of Knowledge (2022 BoK) — cssgb-cert-insert.pdf; Six Sigma Green Belt Certification (CSSGB) — ASQ certification page — Requirements, Examination, Policies and Procedures, Application Process, Testing Dates; ASQ Certification Candidate Handbook — Reference Materials, Calculators, Pencil and Scratch Paper; ASQ Exam Results FAQs — Scoring, results timing, retake policy
What should you expect on the computer-based exam?
The CSSGB computer-based exam contains 110 questions: 100 scored and 10 unidentified, unscored pretest items. You have 258 minutes to answer them; the appointment is 270 minutes.
ASQ uses a scaled passing score of 550 out of a possible 750. This is not a raw percentage or a fixed published number of correct answers. A practice-test percentage cannot be converted into the official scaled result.
Check the current registration page and candidate handbook for the language, delivery mode, application dates and fee that apply to your booking. Paper-based forms can differ from the computer-based figures above.
Sources: The ASQ Certified Six Sigma Green Belt certification brochure and Body of Knowledge (2022 BoK) — cssgb-cert-insert.pdf; Six Sigma Green Belt Certification (CSSGB) — ASQ certification page — Requirements, Examination, Policies and Procedures, Application Process, Testing Dates; ASQ Certification Candidate Handbook — Reference Materials, Calculators, Pencil and Scratch Paper; ASQ Exam Results FAQs — Scoring, results timing, retake policy
What does open book allow?
Use securely bound references and notes that remain bound during the exam. Electronic reference copies and collections of questions and answers are prohibited by the candidate handbook.
Prepare any permitted tabs before entry. If a reference contains practice questions or refresher quizzes, follow the handbook’s requirement to remove or obscure them. Studying with a question bank does not make it a permitted exam reference.
Confirm calculator and scratch-work rules for your delivery mode. A test-center appointment supplies scratch paper; remote testing uses the software Scratchpad. Do not apply the test-center paper rules to a remote exam.
Sources: ASQ Certification Candidate Handbook — Reference Materials, Calculators, Pencil and Scratch Paper
Sources
Facts checked against ASQ sources, September 2026: