Improve Phase in Lean Six Sigma: Designing, Testing, and Implementing Better Solutions

What Is the Improve Phase?

The Improve phase in Lean Six Sigma focuses on developing, testing, and implementing solutions that address validated root causes identified during the Analyze phase. It is where ideas are translated into action, using structured experimentation and data-driven decision-making to optimize process performance, eliminate waste, and achieve measurable improvements.

Why the Improve Phase Matters

The Improve phase is critical because identifying root causes alone does not create value—sustainable improvement comes from implementing effective solutions.

Organizations that excel in this phase:
Convert analysis into measurable results
Reduce defects, variation, and waste
Improve efficiency, quality, and customer satisfaction
Minimize risk through controlled testing before full implementation

Without a disciplined Improve phase, organizations risk implementing ineffective solutions, introducing new problems, or failing to realize the full benefits of their analysis.

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Key Concepts in the Improve Phase

🔹Solution Generation

Developing a range of potential solutions using structured methods such as brainstorming, benchmarking, and innovation techniques to address root causes.

🔹Solution Selection

Evaluating and prioritizing solutions based on feasibility, impact, cost, risk, and alignment with organizational goals.

🔹Pilot Testing

Testing selected solutions on a small scale to validate effectiveness and identify unintended consequences before full implementation.

🔹Design of Experiments (DOE)

Using statistical methods to systematically test variables and determine the optimal combination of factors influencing process performance.

🔹Process Optimization

Refining process inputs and configurations to achieve the best possible performance outcomes with minimal variation.

🔹Error Proofing (Poka-Yoke)

Designing processes and systems to prevent errors from occurring or to detect them immediately when they do.

🔹Implementation Planning

Developing a structured plan to deploy solutions, including timelines, responsibilities, resources, and communication strategies.

Common Tools Used in the Improve Phase

A Note on Tool Selection: While the following tools are commonly used in the Analyze phase, not every tool is required for every project. The selection of tools depends on the nature of the problem, the process being studied, and the type of data available. Effective Continuous Improvement practitioners focus not on using more tools—but on using the right tools at the right time. The goal is not complexity, but clarity and confidence in overall understanding of behaviour.

🔹Value Stream Mapping - Future State

Construct a future state value stream map that provides a visual, strategic "blueprint" to show how a process should operate to eliminate waste and maximize efficiency once planned improvements are implemented.

🔹Failure Mode and Effects Analysis (FMEA)

Make improvements on prioritized process, product, or service risks identified in the FMEA,, including error-proofing (aka "mistake-proofing, "poka yoke"), detection, and control methods.

🔹Poka Yoke (Mistake/Error-Proofing)

Identify and apply error-proofing techniques for the purpose of eliminating or reducing identified risk of failure in process, product, or service.

🔹Daily Huddles

Implement daily lean huddles, (5–15 minute standing meetings) to facilitate alignment of teams, improve communication, and foster and promote continuous improvement and "Lean Thinking".

🔹5S (Sort, Set in Order/Straighten, Shine/Sweep, Standardize, Sustain)

Implement 5S (aka "6S") to improve the workplace by creating a more organized, clean, and safe environment that boosts productivity and efficiency.

🔹Visual Workplace

Implement visual workplace to improve efficiency, safety, and productivity by communicating key information when and where it is needed to reduce waste and errors, minimize time spent searching, reinforce training, and enhance safety awareness.

🔹Standard Work

Develop and implement (or update existing) standard work that documents the approved method ("best practice") for performing a task or operation with a goal of increased efficiency, higher quality, improved safety, and predictable, reliable customer experience.

🔹Kanban

Design and implement "kanban systems" for visualizing workflow and/or inventory, limiting work-in-progress (WIP), and focusing on flow efficiency, to reduce bottlenecks, eliminate multitasking, reducing inventory, and boosting productivity.

🔹Work Leveling (aka "Heijunka")

Implement work leveling to smooth out the volume and mix of production over a set period with a goal to minimizing waste by producing a consistent, average quantity of goods on a daily basis that is more aligned with customer demand.

🔹Cellular Manufacturing and Improved Office Layout and Design

Apply the principles of work cell design to maximize operational efficiency and reduce waste by reorganizing resources—such as people, machines, and materials—into a compact and more logical, streamlined arrangement that minimizes waste, including motion and transportation on the shop floor and in the office.

🔹Rapid Changeover (SMED, "Single Minute Exchange of Dies")

Applied to both manufacturing and service/administration, apply rapid changeover methods to minimize the time equipment or processes remain idle ("downtime") when switching from one product or task to another, thereby delaying the processing of another part or the service of another customer.

🔹Total Productive Maintenance (TPM)

While not a standalone improvement tool or method, the purpose of Total Productive Maintenance (TPM) is to maximize production equipment efficiency and reliability by creating a proactive, company-wide culture that eliminates waste, breakdowns, defects, and downtime. Among other things, TPM empowers operators to perform basic maintenance and aims for zero breakdowns, zero accidents, and zero defects... principles that can be applied in an office environment.

Where Improve Fits in the DMAIC Framework

The Define phase sets the foundation for all subsequent phases:

Define – Identify the problem and customer requirements
Measure – Understand current performance using data
Analyze – Identify root causes of issues and process improvement opportunities
Improve – Design and Implement solutions
Control – Lock in changes and sustain the improvement gains over time

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