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Letting fly with six sigma

James Wright

Manufacturing Digital

13 June 2013 


Six sigma is a continuous improvement approach and toolset – developed in the manufacturing sector by Motorola in the 1980’s – used to reduce the number of deviations or errors created from a process.

The name six sigma derives from a term used in statistical mathematics called standard deviation, a measure of the deviation of a data set from its mean (represented by the symbol σ, sigma). The term six sigma generally refers to a defect rate in the single digit range of parts per million, which was the original target set by Motorola.

The concept 

Once the number of defects in a process has been measured, it can be worked on to reduce it to as close as possible to zero. The value this provides to organisations means that products sold are robust with zero defects. This enables the generation of high levels of customer satisfaction and low cost of warranties, rejects and returns.

Since it was developed six sigma has become well known for:  

1) Being adopted by Jack Welch at GE in the 1990’s as a core driver of continuous improvement, and is now a fundamental part of GE’s culture  

2) Adopting the black belt system of certification which accredits practitioners depending on their level of learning and quality of six sigma projects undertaken

3) The Define, Measure, Analyse, Improve & Control approach (DMAIC). This is a derivative of Deming’s Continuous Improvement Cycle PDCA – Plan, Do, Check Act – and is used to bring structure to the continuous improvement of a process

The top tips:

Get going – while a level of theoretical training is important, many people learn better by doing. It is a practical tool so use it this way.

It’s often better to get the approach 70 percent correct and make a difference quickly, rather than labouring to get the approach 100 percent correct and never get to an implemented solution. You need to establish a real drum beat for continuous improvement.

To apply or not to apply that is the question – there is often a challenge between the advocates of six sigma and lean approaches as to the right approach to follow.

This apparent conflict can be distracting to those just concerned with trying to improve the performance of their business, to the extent that within large organisations advocates of different methodologies often compete to resolve the same problems, wasting time and resource.

Neither approach is the curer of all ills; all continuous improvement tools should be applied subject to the problem you’re trying to solve. They are all part of the broad continuous improvement toolset and it’s the understanding of what each tool can give you that is important. The way forward is to collaborate to solve problems in the best way possible.

Six sigma’s primary use is to reduce the variation of processes with statistically significant outputs. It’s best applied when these process outputs are critical to quality and critical to business performance.

Link to business performance – the six sigma toolset is without a doubt powerful; however this will not be seen when applied to problems that have no bearing on business performance.

To gain most value there needs to be an exercise up front linking the application of tools, effort and energy with the highest priorities for business performance; whether through the use of balanced scorecards, policy deployment, business strategy or other means.

Innovate – often the biggest barrier to driving significant performance improvement and value using six sigma is being restricted by conventional thinking.

The problem is common, cultural and often hard to see and resolve. Unconstrained thinking is the key, which can be encouraged by internal collaboration with multi-functional teams; external collaboration through the involvement of customers, partners and suppliers; open innovation and building a culture where people can challenge the norm freely.

Warning, experts only! – while the certification systems associated with six sigma are great in acknowledging excellence and achievement in the field, it can feel like six sigma is the reserve of experts.

Our experience this is certainly not the case. Experts have an important role to play with respect to coaching and facilitation, but heavy involvement by experts or projects resourced only with experts can be counter-productive.

Six sigma usually benefits from a variety of different viewpoints, experts in the tool-set, those who know the process well and those who are new to the process. Continuous improvement works well when everyone is encouraged to contribute rather than feel excluded from it.


James Wright, manufacturing expert at PA Consulting Group  


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