Lean -v- six sigma

photo credit: Woody Thrower

Lean and Six Sigma are both planned change initiatives with objectives to reduce or eliminate waste but there the similarity ends.

Both are often referred to as programs, but that is not accurate. Six Sigma may be a program but lean is a philosophy. As a program, Six Sigma uses a methodology called DMAIC (determine, measure, analyze, implement, and control) to identify and eliminate waste. As a philosophy, lean is about continuous improvement through the elimination of waste.

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Lean

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Six sigma

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People
Six Sigma is about exclusion. A Six Sigma team is identified for a specific area or project. The team may include several Green Belts led by either a Black Belt or Master Black Belt. The team may disappear for several days of extensive training in DMAIC, team building, communication, and so forth, before they start plotting and gathering data for their “six sigma” project. Because of the complexity of Six Sigma, it does not make business sense to train everyone, or assign all employees to projects.

There is great excitement within the Six Sigma project team: learning, participating, and contributing. But everyone else becomes a bystander, waiting for change that may or may not have included his or her participation.

Countless stories tell of huge successes and cost savings from six sigma projects. Testimonials abound as trade publications provide articles on Six Sigma. I have even witnessed and led some of these successes in accounting, material management, and manufacturing.

However, generally, only the manufacturing people know about the manufacturing projects; only the accounting staff knows about the accounting projects; and only the materials group is aware of the materials management project. There is little or no participation beyond the project team. While organizations realize huge cost reductions, there is no effect on the culture or the organization as a whole.

What happens at the end of the project? Unfortunately, some six sigma projects become personality driven. When team leader goes on to another project, the team members fade away. Only recently in the spotlight, getting attention and recognition, they now may feel no one remembers them. Has there been a permanent behavior change? When the project loses visibility, will improvement be sustained?

Lean is inclusive. Lean teaches us that success is achieved when the entire value stream improves, not when one discrete element of it does. In a successful lean implementation, the entire organization may be involved in improving the value stream. All systems must be aligned. Purchasing, scheduling, manufacturing, engineering, accounting, and human resources must all be active believers and participants in the lean journey.

Without 100% inclusion, the effort will stall when it reaches the excluded part of the organization. The lean organization educates, engages, and empowers the entire workforce to identify and eliminate waste throughout the value stream

Approach to Change
Transformational change and change management are two approaches to effective implementation of planned changes. As change management, Six Sigma tends to focus on cost, quality, and schedule. This narrow focus is apparent even in the names of project teams: inventory reduction team, accounts receivable cycle time team, manufacturing scrap reduction team, etc.

Lean is a transformational change, one that moves the organization to a planned state. It involves the business strategy, organizational design, structure, culture, and processes of the entire value stream. It creates and reinforces the concept of continual change through the elimination of waste, improving the entire value stream’s effectiveness. A lean change transfers knowledge and creates a learning organization.

Improvement Philosophy
Six sigma is aimed at specific targets in the value stream. The objective is to realize a level of improvement using the structured approach offered by DMAIC. The project teams keep the group focused on specific goals and objectives.

The teams work hard to identify root causes, test hypotheses, validate their analysis, implement their recommendations, and monitor them to ensure expected results are attained. When the projects are complete, the group celebrates, disbands, and the individuals return to their previous jobs. At best, they leave metrics or control charts to prevent rollback.

Control charts, however, only encourage maintaining the status quo. Now before the statisticians get alarmed, remember that for a process to be in control there should be an expected deviation around the average. Processes that show a number of points above or below the centerline are considered “out-of-control.” Unfortunately, even if the trend is positive, indicating continuous improvement, statistical thinking will still consider it out of control. The negative implication can make the typical human being flinch after having made a large investment in time and energy in a Six Sigma project.

Lean is all about continuous improvement. The philosophy says there will always be waste to be extracted from the value stream. Lean is an ongoing celebration of waste removal, a never-ending process. In the transformed learning organization, members are continually building skills and improving, making lean a daily part of their lives.

Summary
The differences between lean and six sigma are greater then the similarities. When the differences are recognized, returns can be maximized by knowing when lean or six sigma is the right choice.