Kaizen, Lean, Six Sigma - What's the Difference?

Kaizen, Lean, and Six Sigma are all business improvement approaches.  They can be thought of as three different tools in the business leader’s toolbox.  It is important to understand the focus and purpose of each.  Using the wrong tool will not fix the problem, and it may make things worse.  As an illustration, if I have three tools: a hammer, a screwdriver, and a wrench; I must use the correct tool to accomplish my goal.  I must use a hammer to drive a nail; a screwdriver will not do the job.  However, if I need to remove the cover of a light fixture from the ceiling, I will want to use a screwdriver.

Kazien

Kaizen can be summarized as, “Fix the next problem.”  Kaizen is a team-based problem solving technique.  Kaizen puts focus on a problem to understand it and solve it – then on to the next for continuous improvement.  A Kaizen project is normally requires only a few days to complete.  The Kaizen team is usually dedicated to fixing the problem during those few days. 

The Kaizen team employs data collection techniques and uses basic problem solving tools to understand the root cause(s).  They then create a solution (within the boundaries and constraints given them by management – such as budget or time) and an implementation plan for the solution.  Often the Kaizen team is empowered by management to immediately implement their solution. 

Kaizen works very well with problems that have a singular root cause, or to improve new and emerging business processes that have “low hanging fruit.”  Kaizen is not as effective at solving complex system problems or transforming an entire business operation. 

Lean

Lean can be summarized as, “Eliminate waste from the flow.” Lean is a process analysis problem solving technique.  Lean focuses on mapping a business process flow and identifying all areas of waste – time waste, cost waste, and wasted activity. 

A Lean analysis for a process normally takes one week to one month, (depending upon the nature of the process).  Once the analysis is completed and solution options identified, the implementation of change can take several days to several months, depending upon whether facility or system changes are needed.  Lean will consider all aspects of how a process is performed, from the process controls, operator training, facilities and systems used, and the process measurements.  Often the team conducting the Lean project is the same individuals with day-to-day management responsibility for the process.  They will lead the change implementation. 

Lean works very well for improving business processes that have a continuous or regular flow.  Lean is not as effective for processes that are only occasionally performed or for problems that have suddenly emerged.

Six Sigma

Six Sigma can be summarized as, “Remove variation.”  Six Sigma is a process control problem solving technique.  Six Sigma focuses on measuring the outputs from a process, aligning those outputs with customer expectations, and then controlling the process so that the outputs stay aligned.  Six Sigma uses a structured five phase project management approach: Define, Measure, Analyze, Improve, and Control.  Six Sigma establishes a permanent management control system to ensure the process maintains a minimal amount of variation in process output. 

A six sigma analysis will normally start with several weeks of data collection, once the real-time data collection system is established.  The data will undergo statistical analysis to understand all sources of variation so that they can be either eliminated or controlled.  This often takes weeks or months to complete the analysis and testing of hypotheses.  The new control system is then implemented and used for day-to-day management of the process by process operators and managers.  Because of the extensive use of statistical analysis, often a Six Sigma team will include several people with process knowledge and several people who are Six Sigma Black Belts or Green Belts.  The solution will often require a change in management control processes and procedures and usually requires changes or upgrades to various business systems. 

Six Sigma works very well with complex business systems that have known performance goals.  Six Sigma is not as effective with processes that have changing requirements.  Also, Six Sigma is a cultural change for management and employees since all process control decisions are data-driven rather than using intuition.  Management no longer is providing direct process supervision, but is acting more as a coach, facilitator, and strategic decision maker.   Operators are now responsible for making the day-to-day decisions required to achieve desired process performance.  This culture change can take a long time.

Comparison

Kaizen	Lean	Six Sigma
Cross functional team	Process management team	Team with process knowledge and statistical expertise
2 -5 days	2 weeks to 2 months	3 – 6 months
Find and fix a problem with clear root cause(s)	Improve process flow – time, cost, and quality	Control process output to consistently meet customer expectation
Typical Tools: data collection, brainstorming, root cause analysis, basic quality tools	Typical tools: value stream mapping, data collection, process analysis tools, Kanban, value-added time	Typical tools: data collection, process capability analysis, statistical hypotheses testing, Gage R&R, DOE, control charts
Limitation: Has difficulty addressing complex problem	Limitation: Requires a consistently used stable process	Limitation: requires expert knowledge and culture change

Synergy

These approaches can be used simultaneously and in concert with each other.  A few example scenarios are described below.  These are for illustration only; your business conditions may not precisely fit these:

• A new operation is having many problems at startup.  I would start with Kaizen projects to solve any “Crisis” problems and begin to establish some predictable performance.  Once the big problems are resolved, I would follow with implementing Lean to remove waste and inefficiency from the process.  This will improve cycle time, cost and quality.  I would then implement Six Sigma to establish a control system to manage the process.
• An existing operation is undergoing a major upgrade for new products or systems.  I would start with Lean.  Map the old and new processes to understand and communicate the changes.  As the new process is introduced, I would assign Kaizen teams to resolve unexpected problems that arise.  Once the new process is stable, I would implement Six Sigma to establish a control system to manage the process.
• An existing stable process does not meet industry benchmarks for cost or quality.  I would start with Six Sigma to ensure the process is aligned on customer value and then determine the issues within the process.  If issues are due to singular root causes, I would use Kaizen teams to solve those problems.  If the issues are due to systemic problems with organizational processes, I would use Lean to understand and improve the process.  (If issues are due to complex business and system interactions that are inherently unstable, I would not use either of these techniques but would rely on a Design of Experiments analysis.)

Business conditions should be used to determine an approach that is best suited for achieving your goals and objectives.