Which DMAIC phases are primarily involved in identifying root causes and testing solutions to reduce defects?

• A. Analyze identifies root causes; Improve tests and implements solutions.
• B. Define and Measure only.
• C. Control is the only phase involved in root cause analysis.
• D. Do and Study restore the original process.

Answer: (A)

The phases involved are Analyze for identifying root causes and Improve for testing and implementing solutions to reduce defects. In the Analyze phase, you dive into data to uncover why defects occur, using tools like cause-and-effect diagrams, regression analysis, hypothesis testing, and process capability analysis to pinpoint the true contributors to defects. Once those root causes are known, the Improve phase focuses on developing and testing solutions—often through experiments or pilots, such as design of experiments or small-scale trials—to confirm that the changes will reduce defects before wider rollout. Define and Measure set up the project and establish baseline performance, but don’t center on root-cause analysis or testing solutions. Control aims to sustain the gains after changes are made.