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Author Topic:   Six Sigma
David McGan
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Posts: 19
From:Henderson, KY, USA

posted 09 July 1998 02:12 PM     Click Here to See the Profile for David McGan   Click Here to Email David McGan     Edit/Delete Message   Reply w/Quote
How would the "Six Sigma" philosophy be best quantified? "Statistical technique", Continuous Improvement activity, Lean Manufacturing, or "all of the above?"

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Marc Smith
Cheech Wizard

Posts: 4119
From:West Chester, OH, USA

posted 11 July 1998 01:38 AM     Click Here to See the Profile for Marc Smith   Click Here to Email Marc Smith     Edit/Delete Message   Reply w/Quote
I don't know about lean manufactuiring, but 6 sigma fits Statistical Techniques and Continuous Improvement.


-> Date: Tue, 23 Sep 1997 17:44:22 -0400
-> From: Dan Rand
-> Subject: 6 Sigma history
-> Let me add another perspective to Six Sigma. IBM executives started
-> visiting Motorola headquarters shortly after they won their Baldrige, to
-> benchmark and pick up some of their quality practices. First on the list
-> was Six Sigma. I was an internal statistical methods consultant and
-> quality engineer at IBM in Rochester, MN at this time. We were forced to
-> adapt Six Sigma at our site, even though we had the same concerns that have
-> been listed in recent discussions in this forum. Six Sigma was present, but
-> not dominant, by the time our IBM site won a Baldrige in 1990.
-> Six Sigma was being implemented corporate-wide at the insistence of some
-> highly placed IBM executives. There were complaints and discussions
-> throughout IBM until the leading technologist in the company called 15-20
-> statisticians and quality managers together to publish a position paper on
-> Six Sigma. We were encouraged to believe that our opinions and factual
-> evidence were going to get a hearing.
-> We expressed concern with Motorola s misuse of statistical terms, the thin
-> theoretical and practical evidence for the 1.5 sigma shift, and the dubious
-> means of counting defects and opportunities for defects. Our position
-> paper was finally regarded as too disruptive to IBM s progress in defect
-> reduction, which management wanted to credit to Six Sigma policies. The
-> position paper was never distributed beyond the team that created it.
-> Six Sigma is rarely mentioned around IBM anymore. It quietly disappeared
-> with the radical downsizing that took place from 1991-93, even though it
-> was always touted as not just another quality program. I believe its
-> disappearance did occur primarily because many of its champions either left
-> IBM, or had too many higher priorities left to cover. I left IBM in the
-> downsizing, along with 80ently state that there is still a passionate pursuit of
-> defect reduction and quality improvement at Motorola, which more or less
-> still occurs under the banner of Six Sigma. We might dismiss the whole Six
-> Sigma approach as sloganism, but we must realize that large corporations
-> necessarily put a simple label on programs that they want to implement
-> corporate-wide. Seemingly, everyone in Motorola knows just what you are
-> talking about when you mention Six Sigma, even if it is different than what
-> we quality experts and statisticians know it is. Their quality improvement
-> process has stood the test of time.
-> IBM could not sustain its Six Sigma program, probably because of business
-> factors. Every organization and their circumstances are a little
-> different. I respect General Electric s CEO and their attempt to fully
-> embrace quality improvement. They may succeed if they get their entire
-> workforce to approach quality improvement with a simple, tools oriented,
-> common sense process underneath the slogan of Six Sigma.
-> Daniel R. Rand
-> Consultant, Rand Quality Technologies
-> ...

[Note: This message was edited by Marc Smith]

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David McGan
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Posts: 19
From:Henderson, KY, USA

posted 14 July 1998 11:45 AM     Click Here to See the Profile for David McGan   Click Here to Email David McGan     Edit/Delete Message   Reply w/Quote
Thanks, Marc, for the information from IBM. Although I had heard a little about 6 Sigma and its successes in the past (mostly associated with Motorola), I'm trying to get much more intimately acquainted with it since my company's President asked me to. So far, I've seen much more of the "mixed emotions" as reported by IBM staffers than completely positive reports. I'm attending a 6-Sigma symposium next week and so should hear plenty of the "pros" of 6-sigma. However, I would also welcome additional input from the less biased "real world." That way, I can make the most informed recommendation as to the direction our company should proceed. We certainly don't want to foster a "flavor of the month" perception with our team members.

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Marc Smith
Cheech Wizard

Posts: 4119
From:West Chester, OH, USA

posted 14 July 1998 02:01 PM     Click Here to See the Profile for Marc Smith   Click Here to Email Marc Smith     Edit/Delete Message   Reply w/Quote
I know I went into this at length somewhere but I can't find where. I included the snippet as it pretty well states a view I feel has to be considered - one specific is the 'theroetical' 1.5 sigma shift which very, very often comes up. Like democrats and republicans there are some real strong opinions on that shift.

I do have a copy of an internal Motorola booklet titled "Six Sigma Process Control" from 1993 but I can't post it or copy it because it's proprietary - internal to Motorola. It's almost 50 pages and is really informative. It's sorta a short version of a book I have from IBM's Quality Institute (approx. 200 pages). Both take a high level approace but IBM's is more extensive (even covers Design of Experiments!)

Anyway, hope the info helps. If you have an friends internal to Motorola you might try to pry a copy of their book. I got the IBM book some years ago (it's from November 1984) and can't remember where. It's a good one.

The point is - both books give parts of what QS9000 lingo calls APQP - which is just a good, sound business system - from product conception / contract review to end of product life. I can't stress highly enough the importance of a robust (for lack of a better word) design 'phase'. If you fail that phase control and things like 6 sigma won't mean much - you cripple yourself early.

Phew - I gotta get back to work!

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Marc Smith
Cheech Wizard

Posts: 4119
From:West Chester, OH, USA

posted 08 May 1999 01:50 PM     Click Here to See the Profile for Marc Smith   Click Here to Email Marc Smith     Edit/Delete Message   Reply w/Quote
Date: Sat, 1 May 1999 15:40:58 -0400
From: RNav
Subject: Re: FW: Six Sigma

In a message dated 4/27/99 11:36:44 AM, NML writes:

>Dear Mr Robert,
> we are a flow control equipment manufacturing
>engineering company with ISO 1901 accreditation. Two years ago we have
>started BPR in a big way and concentrated to improve key processes. How
>ever we have not improved the quality management process. Of late we
>have started getting more customer complaints signaling that quality is
>going down.
> can you throw some clarification on the following?
>* what are the organizational pre requisites to start the
> six sigma process?
>* is there any guide book that is practical and
>implementation oriented?
>* what role training should play in propagating six sigma
>Thanks ®ards
>Senior Deputy General Manager(BPR)
>CHENNAI-600 089
>INDIA ph:044-2322323
> fax:+91(44)2325055

BPR is an interesting phenomenon. It is a powerful technique, but if not implement by including those you are being BPR'd, chaos can result, since bad feelings can be generated in the whole organization. But I stray:

"However we have not improved the quality management process. Of late we have started getting more customer complaints signaling that quality is going down."

With this statement, my take is that you BPR'd some processes, but never looked at how management works. If you change the processes, but management doesn't change they way they manage, that can lead to a lot of trouble. The new process may rely on a certain level of autonomy, and reduced cycle times. If management doesn't adjust to that, you just get into trouble at a reduced cycle time. In this aspect, I would focus management on having proper measures (unbiased by politics), reviewed periodically (monthly is good), and action plans to close gaps. This is essentially a page from Demings PDCA (Plan-Do-Check-Act cycle for improvement).

"can you throw some clarification on the following? * what are the organizational pre requisites to start the six sigma process?"

The prerequisites are the same for any other type of systematic process improvement effort; *management understand of the changes that the new system will require *management leadership in implementing the change *unwaivering support when the road gets a little bumpy during the change *a focus on the process and achievable results, early wins help in the change process

"* is there any guide book that is practical and implementation oriented?"

I am currently not aware of a book, though I think some are in the offering. Motorola University has some books that may help. I would check with WWW.AMAZON.COM and check their offerings too. I would also review any and all books on change management. "The TEAM Handbook" by Peter Scholtes is a good implementation tools and a good overview.

"* what role training should play in propagating six sigma movement?"

It is absolutely vital. GE trains all managers who want to pursue a promotion and career with the company. They have three levels of training for their managers. One is "Black Belts" who receive extensive training (4 months of classroom and practical) and implementation experience. They have a 2 yr tour as a Black Belt and then move into a managers position and are expected to use what they learned in their new position. The other two levels are variations of OJT (On the Job Training).

The current practice is to train a select few for implementation and used them in a dedicated role to improve the business and train others in the methodology.

I hope this helps.

P.S. - In western culture, the last name is the family name, so to be formal and proper, the address would read Mr. Drensek, the informal would be Robert, but I usually go by Bob.

Robert Drensek, CQE, CQA, CRE, CMI
Quality Engineer

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Don Winton
Forum Contributor

Posts: 498
From:Tullahoma, TN

posted 10 May 1999 10:40 AM     Click Here to See the Profile for Don Winton   Click Here to Email Don Winton     Edit/Delete Message   Reply w/Quote
Good post!

More on six sigma can be found at:

Although I cannot recommend any of the titles (I have not read them), a lot of six sigma publications can be found at:


Just the ramblings of an Old Wizard Warrior.

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Marc Smith
Cheech Wizard

Posts: 4119
From:West Chester, OH, USA

posted 20 January 2000 03:47 PM     Click Here to See the Profile for Marc Smith   Click Here to Email Marc Smith     Edit/Delete Message   Reply w/Quote

The other Six Sigma threads to date are:

[This message has been edited by Marc Smith (edited 20 January 2000).]

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posted 24 January 2000 11:16 PM           Edit/Delete Message   Reply w/Quote

One could achieve 100 sigma, (that's lots more sigmas than 6!), yet if the product you are producing cannot tolerate temperature changes, for example, then you will quickly be out of business. This is but one of the many flaws in this compilation of management, and statistical tools.

I have found the six sigma program to be a repackaged set of tools that did not work very will the first time around, and not likely to work the second. Mostly devoid of engineering and cost considerations, I find it problematic for use in hi-tech industry.

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Scibilia Bruno
Lurker (<10 Posts)

Posts: 2
Registered: Feb 2000

posted 21 February 2000 06:15 AM     Click Here to See the Profile for Scibilia Bruno   Click Here to Email Scibilia Bruno     Edit/Delete Message   Reply w/Quote
I have recently been visiting a GE plastics plant in the Netherlands. My impression was that six sigma' there, has more to do with continuous improvement, setting hard-to-achieve objectives and team leadership than with statistical techniques.
The capability indices (Cp, Cpk, Cpm) already provide effective metrics to assess a process performance.
Six Sigma assumes that the process deviates by 1.5 sigma (sigma is the standard deviation) from the desired value. Therefore Six Sigma corresponds to a Cp of 2, a Cpk of 1.5 and a Cpm of 1.11. The reason why Six Sigma does not perform so well in terms of Cpm is that, Cpm (rightly) gives a greater weight to the bias component from the desired value (1.5 sigma).
When Six Sigma is used as a quality measure, much effort is likely to be spent trying to reduce the process variance (so that the standard deviation represents only one twelwth of the specification interval) whereas adjusting the process to the desired value would often be a more effective and less expensive strategy. This is even truer when the response is autocorrelated (which often happens in practice) and the process needs to be be continuously adjusted.
To reduce quality losses, one should first adjust and monitor the process using Statistical Process Control or Engineering Process control to ensure that the bias is eliminated.

Cp = (USL - LSL) / 6 sigma
where USL is the upper specification limit
and LSL is the lower specification limit
Sigma is the standard deviation

Cpk = Min {([USL - m]/3 sigma),([m - LSL]/3 sigma)}
where m is the average

Cpm = (USL - LSL) / [6(sigma+(T-m))**0.5]
where T is the desired value

Nota bene : Please note that **0.5 means square root. I cannot convey the square root symbol.

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Marc Smith
Cheech Wizard

Posts: 4119
From:West Chester, OH, USA

posted 14 May 2000 01:06 PM     Click Here to See the Profile for Marc Smith   Click Here to Email Marc Smith     Edit/Delete Message   Reply w/Quote
From: Terry Peterson
Date: Thu, 11 May 2000 21:54:22 +0100
To: den.list
Subject: six sigma

Not this again, I hear the world-wide groan.

I don't intend to prolong the discussion. I just wanted to thank the many good people who responded to my original request for help. It has helped me resolve the client issue.

Below is a summary of the responses. I am not able to acknowledge all the contributions, if you see your words, please take it as a sincere compliment.


First and foremost Six Sigma is a BUSINESS. The Six Sigma Academy in Scottsdale, Ariz., is run by former Motorola quality experts Mikel Harry and Richard Schroeder, who rope steers in their spare time and pose for publicity pictures in cowboy hats and boots. Their fees start at $1 million per corporate client. It's expensive to implement, so it has been a large-company trend.

Most people responded that there is not an affordable way to learn Six Sigma well without attending "THE ACCADIMY." This explains why I couldn't find any books that explain what six sigma is and how to do it; and why Harry's books and articles are heavy on promoting benefits and light on details. They aren't about to give the store away! ASQ has decided to make Six Sigma training affordable to small and midsize companies. But even though trainees from different companies are grouped together, it still costs $35,000 to $40,000 a person. Despite this, there's a waiting list.

Six sigma does indeed have an attractive message for CEO's - save millions on the bottom line. Put the resources in place, get the people trained up and they'll big savings in waste reduction and efficiency gains. About 30 companies have embraced Six Sigma including Bombardier, ABB (Asea Brown Boveri) and Allied Signal. But it's capturing widespread attention because of two heavyweight disciples: CEOs Jack Welch of GE and Bossidy of AlliedSignal. They are arguably the most influential executives in business today; they talk to each other on the phone weekly and encourage their employees to share Six Sigma discoveries between companies.

What is it? I was stuck for info. However, it turns out that two guys from my client had been trained as black belts in mid 90's, although they hadn't been able to make much use of it. So, I was able to study their material in depth, and I was able to confirm that Six Sigma uses bog standard statistics, process management and continual improvement techniques in a nicely packaged, well promoted marketing proposal. First up, it is NOT Deming based: there is no concept of SoPK; despite the heavy doses of statistics, spc and process behaviour charts are relegated to process monitoring; and a major element uses Juran's breakthrough strategy for quality improvement projects.

In his current QP articles, Harry says "In most cases, what we see is alphabet soup--a wide array of programs and initiatives that may or may not work consistently toward the same end by the same means. We see a cornucopia of well-intended and sometimes disconnected interventions struggling to coexist under one corporate umbrella. In other words, while the people in charge of the processes and operations of the company are focused on the real expectations of the customer, the company's executives are focused on the real and perceived economic needs of the business. While both factions are trying to achieve their aims independently, often there are mismatches among the customers' needs, the needs of the provider and the inherent capability of the systems by which these needs are aligned, connected and improved. The crux of the issue is that the business of making profits has been too large for any one specific management intervention. Although useful initiatives have been present for a long time, and although they have seemed perfect on paper, they have never functioned as an integrated whole. We have lacked a holistic focus, an approach that could align and leverage the various initiatives in a harmonious and simultaneous manner.

Dead right Mikel! However, we already have an holistic framework - it's called SopK!!

He goes on, "We at the Six Sigma Academy believe our new definition of quality can provide the organising focus the quality movement needs .. Six Sigma, focuses concurrently on all elements of the matrix, moving a company toward entitlement in all dimensions of business. Via the Breakthrough Strategy, Six Sigma brings the entire mosaic of the matrix under one umbrella. In this way it provides a complete framework for balanced and profitable corporate turnaround".

Good words but, on closer inspection, six sigma in action doesn't match this rhetoric. Nice packaging and good promotion don't add up to add up to a soundly-based philosophical framework for running an organisation. The training concentrates on advanced statistical methods that demand a relatively high degree of mathematical ability. It depends on measureables attained to keep it alive in the eyes of the top level management, to keep it interesting to the people affected by it, and to sustain the "priestly caste" of the black belt. The programme is very intensive, one black belt likened it to 'drinking through a fire hose'. Most of it is surplus to requirements.

Harry outlines the basic framework of six sigma as;

-- Highly visible top-down management commitment to the initiatives.

-- A measurement system (metrics) to track the progress that are integrated into business strategy. This weaves accountability into the initiatives and provides a tangible picture of the organisation's efforts.

-- Successful six sigma efforts are supported with a framework of process thinking.

-- Internal and external benchmarking of the organisation's products, services, and processes. This requires disciplined customer and market intelligence gathering.

-- Six sigma projects must produce real savings.

-- Stretch goals to focus people on changing the processes by which the work gets done, rather than "tweaking" the existing processes. This leads to exponential rates of improvement.

-- Educating all levels of the organisation. Without the necessary training, people cannot bring about breakthrough improvement.

-- Success stories to demonstrate how the Breakthrough Strategy is applied and the results.

-- Champions and Black Belts to promote the initiatives and provide the necessary planning, teaching, coaching and consulting at all levels of the organisation.

-- Developing a breakthrough philosophy.

-- Leaders support and reward initiatives and the improvement teams that carry them out

Again good words, but there are concerns about this in practice. Right from the start of six sigma training the 'bottom line' financial gain from projects is the key project driver. Customer focus is of secondary importance; in the real world the first question the black belts have to answer is "How much will this project save?". Short term thinking does not provide long term benefits derived from improving processes by working with a customer on what their expectations are. One of the advantages advantage claimed for six sigma is its addition of resources, the corps of highly qualified business process improvement experts (the green, black, and master black belts) who wield the tools needed to achieve the enterprise's strategic objective. Expensive to train (up to US$30,000 per belt) and deployed for the medium to long- term, these highly motivated and skilled individuals focus on corporate sponsors (for the leverage required to overcome resistance to change, obtain additional resources, and align strategic objectives), make sure that the right metrics are identified, and continually signpost progress to cement-in both corporate and front-line commitment. Six sigma programmes call for "the best people" to be trained as black belts.

However respondents cite two issues with this:

-- Quality improvement is made to seem difficult and the prerogative of the expert. This seems to miss the notion that reducing variation ought to be the job of everyone. The Japanese feel that most workers are capable of learning what is needed to ensure quality and continuous improvement at the line worker level and expect they will study and analyse the quality control process on their own initiative. I believe this to be consistent with Dr. Deming's and Shewhart's opinion as to the learning abilities of the "willing workers."

-- Most quality improvement requires consistent application of basic approaches. Most black belts when interviewed will readily admit that over 90% improvements are achieved with about 20% of the content of the training. This is very wasteful "Where six sigma programs are being effective they tend to be in companies with very directive cultures..... some 'master' black belts are reporting spending as much as 60% of their time on collecting and reporting project data. The bigger drawback, however, is that the moment the management stop driving, all improvement stops"

In my original query, I asked about the 1.5 sigma shift, or the idea that 6sigma actually equals 4.5 sigma. No one was able to cite evidence for this. It seems to be based on a concept of process drift and/or short-term vs. long-term limits. If this makes sense in your system, then it might have some value. Most respondents did not accept it. I also had difficulty with the relevance of 6 or 4.5 sigma. Matching the voice of the customer to the voice of the process is an obvious need. But, how you attach a sigma value to customer entitlement seems to me a mind-boggling concept. Deming said, "It is necessary to innovate, to predict the needs of customers, to give them more". In other words, don't just meet today's perceived needs, continually strive to improve everything, always.

One respondent reported Don Wheeler's comments on six sigma, "Although Six Sigma is obviously based on and derived from the area under a normal curve, it is used as a communications metric, and not a scientific one. It's a way to express the approximate aggregate capability of a process. Understanding it that way requires that you add a new definition for 'sigma' to your vocabulary, but once you do that, it actually becomes a useful communications vehicle. "It is unfortunate that they used the word 'sigma,' because it has such precise meanings in the statistical world (or not, depending upon whom you read)."

Does it work? From the responses, the answer is, "it depends". It probably has utility in areas that involve multi-component assembly, such as advanced electronics. This may explain why GE, Allied Signal, Motorola, et al, have got mileage from it. However, others report that some companies have realised after several years application of six sigma that their customers are not seeing the benefits and are becoming irritated by the constant publicity.

Is the cost justified? Those who make their living by training Six Sigma are not going to stand up and say that it does not provide value. My view is that some organisations may be able to achieve the short term cost savings and justify the cost of training the multi-colour belts. Long term; the jury is still out.

There remains one outstanding issue. Six sigma is essentially predicated on existing in today's Anglo-Saxon, (i.e. British/American), management model. It says, "carry on as you are, and we will show you how to further improve the bottom line". One of my favourite papers (1) suggests that the new management theories cannot be grafted piece-meal onto existing structures, it requires full-scale organisation change, In Deming terms, 'transformation'.

Myron Tribus says that most of the alphabet soup of quality initiatives; ISO-9000, MBNQA, EFQM Excellence Model, etc, can have real value, if they are implemented through a deep understanding of SoPK. The thinking process involved in this understanding means that management simply has transform the way they run the organisation. Six sigma's attempt to eschew this, means that it will inevitably be seen as yet another business fad, nonetheless profitable for those selling it.

I hope this closes the discussion.

(1) TQM's Challenge to Management Theory and Practice, Grant, Shani and Krishnan, Sloan Management Review. Winter 1994

Terry Peterson

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