1.0 Define

Lean Six Sigma Refresher: The Define Phase

The Define Phase is the cornerstone of the DMAIC cycle, setting the stage for successful project execution. For practitioners already certified, revisiting its fundamentals ensures clarity, alignment, and precision in tackling improvement initiatives.

1.1 The Basics of Six Sigma

1.1.1 Meanings of Six Sigma

  • Statistical Definition: Six Sigma represents a process performance level of 3.4 defects per million opportunities (DPMO), signifying near-perfect quality.

  • Philosophical Definition: It is a mindset of continuous improvement, emphasizing data-driven decision-making and customer-centricity.

  • Methodological Definition: Six Sigma is a structured problem-solving approach using the DMAIC framework (Define, Measure, Analyze, Improve, Control).

1.1.2 General History of Six Sigma & Continuous Improvement

  • Origins: Developed at Motorola in the 1980s to address high defect rates in manufacturing.

  • Adoption: Popularized by General Electric in the 1990s, where Jack Welch integrated Six Sigma into GE’s culture.

  • Evolution: Today, Six Sigma is applied across industries—manufacturing, healthcare, IT, finance—often combined with Lean principles to eliminate waste and improve flow.

  • Continuous Improvement Link: Six Sigma builds on earlier quality movements (Deming’s PDCA cycle, Total Quality Management) but adds statistical rigor and financial accountability.

1.1.3 Deliverables of a Lean Six Sigma Project

Key outputs from the Define Phase include:

  • Project Charter: Establishes scope, objectives, and stakeholders.

  • Business Case: Justifies the project’s alignment with strategic goals and expected benefits.

  • Problem Statement: Clearly articulates the issue to be solved.

  • Goal Statement: Defines measurable targets for improvement.

  • High-Level Process Map (SIPOC): Outlines Suppliers, Inputs, Process, Outputs, and Customers.

1.1.4 The Problem-Solving Strategy: Y = f(x)

  • Concept: Expresses the relationship between outputs (Y) and inputs (x).

  • Interpretation: The quality of the outcome (Y) is a function of the critical factors (x’s) influencing it.

  • Application: Guides practitioners to identify and control the vital few inputs that drive process performance.

1.1.5 Voice of the Customer, Business, and Employee

  • Voice of the Customer (VoC): Captures customer needs and expectations, often through surveys, interviews, or complaint data.

  • Voice of the Business (VoB): Aligns projects with organizational priorities such as profitability, market share, or compliance.

  • Voice of the Employee (VoE): Ensures frontline insights are incorporated, fostering engagement and practical solutions.

  • Integration: Balancing these voices ensures projects deliver value across stakeholders.

1.1.6 Six Sigma Roles & Responsibilities

Six Sigma thrives on a structured hierarchy:

  • Executive Leadership: Sponsors and champions Six Sigma initiatives, ensuring alignment with strategy.

  • Champions: Senior managers who remove barriers and provide resources.

  • Master Black Belts: Experts who mentor and provide advanced statistical guidance.

  • Black Belts: Lead projects full-time, applying tools and driving results.

  • Green Belts: Support projects part-time, applying Six Sigma within their functional areas.

  • Yellow Belts: Contribute basic process knowledge and assist in data collection.

Final Thoughts

The Define Phase is more than a starting point—it’s the foundation of project success. By revisiting its principles, certified professionals can sharpen their focus, ensure alignment with organizational goals, and set the stage for measurable, sustainable improvements. Lean Six Sigma remains a powerful blend of rigor, discipline, and adaptability, and mastery of the Define Phase ensures every project begins with clarity and purpose.