The First Principle of Six Sigma

‘Continual Improvement is an ongoing process of change followed by consolidation.’

Every process has a performance curve.

The fundamental error many managers make is to set out to achieve maximum improvement and reach the ultimate performance potential of a process in a single step.

In order to achieve that level of improvement, every single variable that affects performance in that process would need to be identified and fixed. Unfortunately, there is no methodology or tool that can do that.

When this is the goal imposed on improvement practitioners, projects will drag on and seem to take forever to complete. There would simply be too many variables to work with to be able to maintain adequate focus.

The reason why the concept is called “continual improvement” is because it works well when managers recognise that massive momentum can be generated when a small improvement is made and then locked in.

A consolidation period allows the process to become stable with the most recent improvements becoming sustainable. This period of consolidation is then followed by another improvement to the process, which is again locked in during a period of consolidation. And so the process is repeated.

The benefits of the continual improvement approach are four fold:

– Gains or wins are experienced much sooner than would otherwise be realised.

– Gains are more easily locked in and sustained over time.

– The workforce gets comfortable with continual improvement because of the wins being experienced.

– The culture of an organisation can shift to one of continually pursuing improvement.

The Second Principle of Six Sigma

‘Y is a function of multiple x’s, rapid improvement occurs when you focus on the key x’s.’

This is the mathematical way of saying that the output of a process (an output is represented by the term y), is a function of its input and process variables (a variable is represented by the term x). What this means is that variation or changes in y are a direct result of variation or changes in relevant x’s.

In its purest form, the way Six Sigma works is quite simple. The project team is charged with reducing or controlling the variation in a specific variable (y), for example material hardness or tensile strength or useful life cycle of a product.

Using their experience and knowledge of the process the team generates ideas about what it is that causes variation in the y.

Their ‘hypothesis’ extends beyond the first level of causes to lower level variables with the intent of finding the most significant causes of variation.

We know that not all variables have the same degree of impact on the y. Improving y begins with finding the ‘critical few’ x’s that really do cause y to be as it is, and that’s where the strength of Six Sigma comes to the fore.

Using various tools and methods, the project team moves beyond hypothesis by validating which of these variables have the greatest impact on variation in y.

Once these relationships are validated, solutions are generated to treat those variables in such a way that the output metric of the process (output variable y) is what you want it to be. Six Sigma’s DMAIC model provides the framework and tools for finding and controlling those critical few x’s.

More Information

This article is drawn from Australia’s best selling PROCESS MASTERY WITH LEAN SIX SIGMA 2ND EDITION.
For more information Click Here where you’ll discover why this is one of the most important text books in the business improvement world today.

Share This