Could Six Sigma have more harmed than helped?

I started my career in the heyday of Total Quality Management (TQM) in France, beginning of the 1980’s and witnessed over the following years how the TQM trainings and deployments built a quality-aware culture in the companies and spread to everyday’s life.

Over time though, other “Japanese Methods” became fashionable and the hype was on the flavor-of-the-month, something the rich Lean toolbox had plenty to offer.

Quality still was a hot topic, but more for getting ISO9000 certified than delivering greater value to customers. The latter was now more a goal for Lean, seamlessly taking over the TQM legacy.

Then came Six Sigma, rewamping TQM with more math inside and those irresistible colored belts. Six Sigma was not intended to merge with anything else, hence the coining of “Lean Six Sigma” or “Lean Sigma” to describe the attempts to merge the two.

Reflecting on nearly 40 years of evolution of the business philosophies, approaches or methodologies, could Six Sigma have more harmed than helped?

Reminder about Total Quality Management (TQM)

What made Total Quality Management (TQM) “Total” was the aim of embarking ALL employees to participate in working toward a common goal: satisfy the customer.

Group activities (quality circles) were organized in order to get everybody’s brainpower, knowledge or understanding about quality issues and the ways and means to solve them.

A simple toolbox holding basically 7 tools was made available to everybody. Those tools were simple enough that a light training and moderate coaching would suffice for anyone to understand and use them. The required level of math was not more than basic arithmetic operations. Everyone was considered a Subject Matter Expert and was invited to participate.

The 7 tools are (minor variations can be found):

You may check my post about these tools >here<

Once problem solving started, continuous improvement would follow. Besides improving value for customers TQM brought also a sense of purpose to all stakeholders, the understanding of how their daily tasks would contribute to bring flawless products or provide great services to customers, turning them into loyal ones and insuring the future success of the organization.

When Lean came to enlarge the scope, it embedded TQM so that there was a continuum and the same people would keep on with a greater variety of problems to solve.

Six Sigma and its colored layers of expertise

Six Sigma is a different approach in which (originally*) statistical math play a key role.With new mathematical knowledge required, the participants roughly divided in three groups:

  • Those lacking the math
  • Those having limited knowledge of it
  • Those having the knowledge or able to get it

To distinguish the levels, martial arts inspired colored belts were created, making the hierarchy of knowledge and related prerogatives official. From then on the working groups switching from total participation regardless to rank and knowledge in TQM and Lean  to Six Sigma, now divided between the few geniuses and their many servants**.

*Over time some “Six Sigma” programs softened up on data and math, promote almost only DMAIC and 5S

**A great quote (approximately) by Jim Collins’ “Good to Great”

The Six Sigma “aristocrats” define what is to be done and the lower ranking take over the mundane tasks to prepare data and stuff for the masters to do their science on. The low ranking participants, awarded white and yellow belts, are less and less involved and empowered, eventually losing the sense of purpose.

All that made TQM and later Lean so great and acceptable by shopfloor people fades away. Interest also fades, as only few people are attracted by the abstract side and difficulties of statistical math.

On top of that, the Black Belts and Master Black Belts, usually challenged and rewarded on the achievements they lead, keep close control of the rollouts, so that they (purposely) become bottlenecks, a limiting factor to solving more problems.

Now it seems to take ages before getting a problem solved, while it was much quicker to those who have experienced simpler, more practical and pragmatic approaches.

Could Six Sigma have more harmed than helped?

Here we come to the question : Could Six Sigma have more harmed than helped? Well, there is no single answer. Six Sigma proved great to solve tricky problems that required more hard science than the simpler methods and tools.

  • Six Sigma reinvigorated quality when this discipline was turning into ensuring compliance to standards, regardless to results.
  • Six Sigma, just as lean, has been deployed properly and sometimes it was misused.

So everything is not just black or white.

Yet I assume that the bad uses outnumber the good ones, that marketing dressed a scientific method with fancy dresses and greedy promoters sold it as a one-fits-all trendy cure to all troubles.

I therefore do not believe in true overall quality improvement and most of all I fear that this segregated approach, with savvy experts on one side and driven doers on the other, turned many people away from developing their own problem solving skills and being engaged in improvements.

For the latter, yes I believe Six Sigma has more harmed than helped.

Your comments are welcome.

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TOC, Lean and aviation MRO

In a previous post, “CCPM helps shorten aircrafts MRO”, I explained the benefits of Critical Chain Project Management (CCPM) for reducing the aircraft downtime during their mandatory and scheduled MRO.

If CCPM is great and helps a lot meeting the challenge, it will not squeeze out every potential improvement, thus time reduction, on its own.

As I explained in my post Critical Chain and Lean Engineering, a promising pair, “What CCPM per se does not is discriminate added-value tasks and non added value, the wasteful tasks listed in a project in a Lean thinking way.

Conversely, if wasteful tasks remain in the project network, chance are they will be scheduled and add their load (and duration) to the project.

That’s why in aviation MRO (as well as in other businesses), Critical Chain Project Management will not be used as a stand alone but in conjunction with other approaches, like Lean and Six Sigma.

Lean mainly will help to discriminate value-added from non value-added tasks, especially those on the Critical Chain, making them high priorities to optimize, reduce or eliminate.

We did not differently when we started with our client Embraer and while in their service center, I placed Philip Marris in front of the camcorders to present, in situ, two books related to TOC, Critical Chain and Lean in aviation MRO (aircraft Maintenance, Repair and Overhaul).

Note: Critical Chain Project Management is part of the Theory of Constraints Body of Knowledge, hence the title of this post where “TOC” is referring to CCPM.

Chris Hohmann

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5 reasons (at least) to explore Theory of Constraints

Theory of Constraints is a “business philosophy” or “management paradigm” that takes into account the existence of constraints, e.g. limiting factors hindering the organization to achieve more of its Goal.  It focuses on the one that limits the performance of the whole system and strives to achieve more of the organization’s Goal (patient’s treatments, throughput, sales… whatsoever).

>Lisez cet article en français

Theory of Constraints is around since the 1980s but is still barely known. Here are 5 reasons (at least) to explore Theory of Constraints (ToC) and check what good it could do for your organization.

1. Theory of Constraints is not theoretical

The name does not sell and is probably somewhat misleading, but Theory of Constraints is more a body of knowledge than a mere theory and its applications are very real and concrete.

Yes ToC has a lot of metaphoric jargon and it takes some time to get used to it. But after all Lean has a lot of jargon too and makes even people “speak” japanese. Six Sigma has its jargon as well. If you want to share with the community, you have to speak the lingo.

Yet being still “confidential” (this point being discussed later), ToC claims relatively few success stories. Compared to Lean with Toyota, ToC has no such lighthouse, no convincing, undisputable and compelling success story so far. The lack of appealing buzz makes ToC still look theoretical. (In the ToC lingo we call this a Negative Reinforcing Loop.)

2. Theory of Constraints (ToC) is a growth oriented approach

ToC is about breaking the limiting factors and getting more out of the organization’s processes and resources, exploiting wasted precious and scarce capacity.

While many organizations seek survival through cost cuttings and savings – which is limited and potentially deadly – those embracing ToC will challenge expanding their business and growth.

Breaking the constraints is for example drastically speeding up deliveries, getting more out of a very expensive or scarce resource. This could be a factory delivering widgets, a hospital treating more patients or an administration significantly speeding up the delivery of documents.

In project management ToC changes the paradigm and ensures projects to finish on time and more likely within allocated budget.

Any organization achieving its Goal significantly faster and better will soon attract market’s attention and get more demand.

In contrast how many new customers will cost reduction or variability reduction attract?

Which doesn’t mean cost reduction and variability reduction should be disregarded, as we will see right now.

3. Theory of Constraints and Lean make a great pair

ToC is often described as a focusing means/tool/approach (you name it) that is a good catalyst to Lean and/or Six Sigma.

While ToC identifies leverage points and critical root causes of problems, Lean and Six Sigma are great ‘tools’ to exploit the leverage points and solve problems.

The synergy using ToC, Lean and Six Sigma is known as TLS. From what I have experienced, seen, heard or read, ToC is most often used in pair with Lean rather than with SixSigma, or sometimes as a TLS trio.

Good news is all prior investment in Lean or Six Sigma training is still valuable, ToC will simply supercharge them.

With ToC, improvements show on bottom line, which is not always the case with Lean. ToC proposes a structured and logical approach applied system-wide, while Lean initiatives are too often used to chase opportunities to optimize locally, failing to improve globally.

4. Theory of Constraints proposes a consistent framework across all activities

ToC originated in manufacturing and just as many approaches, methods or tools it soon proved usable in other environments.

But unlike some of the others, ToC did not simply transpose into other environments but developed specific tools and approaches for those branches while keeping consistent.

I am thinking about Critical Chain Project Management (CCPM) which revisits project management and corrects the flaws of the Critical Path Method (CPM).

I am thinking about Logical Thinking tackling non-physical constraints such as beliefs, policies or resistance to change.

ToC does also challenge supply chain management, accounting or marketing.

Regardless the various applications, the core concepts of constraints and the scientific approach remain the same.

5. Theory of Constraints is still “confidential”

ToC is not very famous compared or Lean or Six Sigma, but there is an advantage in this ‘weakness’: organizations using ToC and achieving more of their Goal usually outmatch their competitors with a kind of secret weapon.

It happens over and again: a very poorly performing unit achieves a fast, unexpected and surprising turnaround, attracting attention from its peers wondering how this could be possible.

In corporations the now admired unit would share its secret, but it could remain the secret weapon for any organization facing tough competition.

Theory of Constraints is not meant to remain secret, it just failed to get enough attention until now. Those using it to outmatch their competitors will not complain. Those being outmatched or seeking a way to a breakthrough now have 5 reasons to give it a try.

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Why Big data may supersede Six Sigma


Chris HOHMANN – Author

In this post, I assume in near future correlation will be more important than causation* for decision-making, decisions will have to be made according to “incomplete, good enough” information rather than solid analyses, thus big data superseding Six Sigma.

*See my post “my takeaways from Big data” on this subject

In a world with increasing uncertainty, fast changing businesses and fiercer competition, I assume speed will make the difference between competitors. The winners will be those having:

  • fast development of new offers
  • short time-to-market
  • quick reaction to unpredictable changes and orders
  • fast response to customers requirements and complaints
  • etc.

Frenzy will be the new normal.

I also assume that for most industries, products will be increasingly customized, fashionable (changing rapidly from one generation to the next, or constantly changing in shapes, colors, materials, etc.) and with shorter life cycles.

That means that production batches are smaller and the repeating of an identical production run unlikely.

In such an environment, decisions must be made swiftly, most often based on partial, incomplete information, with “messy” data flowing in great numbers from various sources (customer service, social media, real-time sales data, sales reps reports, automated surveys, benchmarking…).

Furthermore, decisions have to be made the closest to customers or where decision matters, by empowered people. There is no more time to report to a higher authority and wait for the answer, decisions must be made almost at once.

There will be fewer opportunities to step back, collect relevant data, analyze them and find out the root cause of a problem, not even speaking about designing experiments and testing several possible solutions.

Decision making is going to be more and more stochastic: with the number and urgency of decisions to make what matters is making significantly more good decisions than bad ones, the latter being inevitable.

What is coming is what Big data is good at: fast handling a lots of messy bits of information and revealing existing correlations and/or patterns to help making decisions. Hence, decision-making will rely more on correlation than causation.

Six Sigma aficionados will probably argue that no problem can be sustainably solved if the root cause is not addressed.

Agreed, but who will care about trying to eradicate a problem that may be a one-shot and which solving time will probably exceed the problem duration?

In a world of growing interactions, transactions and in constant acceleration, time to get to the root cause may not be granted often. Furthermore, even knowing what the root cause is, this one may lay outside of the decision maker or company’s span of control.

Let’s take an example:

The final assembly of a widget requires several subsystems supplied by different suppliers.The production batches are small as the widgets are highly customized and with short life cycle (about a year).

The data survey – using big data techniques – foretells the high likelihood to have some trouble with the next production because of correlations between former experienced issues in combination of some of the supplies.

Given the short notice, relatively to the lengthy lead time to get alternate supplies, and the short production run, it is more efficient to prepare to overcome or bypass the possible problems than trying to solve them. Especially if the likelihood to assemble again these very same widgets is (extremely) low.

Issues are not certain, they are likely.

The sound decision is then to mitigate the risk by adding more tests, quality gates, screening procedures and the like, supply the market with flawless widgets, make the profit and head for the next production.

Decision is then based on probability, not on profound knowledge.

But even so the causes of issues are well-known, the decision must sometimes be the same: avoidance rather than solving.

This is already the case with quieter businesses, when parts, supplies or subsystems are supplied by remote unreliable suppliers and with no grip to control them.

I remember a major pump maker facing this kind of trouble with pig iron casted parts from India. No Six Sigma techniques could help make a decision or solve the problem: the problem laid beyond the span of control.

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Starting a new year: 2015


Chris HOHMANN – Author

The first day of the year 2015 started with a beautiful sunrise, which I saw as a good omen for the 364 days to follow.

The first day of a new year is highly symbolic for a new start, resolutions and hope, even so the same new start, resolutions or hope could happen on any other day in the year.

That’s why my new year started one month earlier, when joining my new company and receiving a lot of kind congratulation messages from my personal / pro network.

Joining this new company brings new exciting perspectives and learning opportunities.

Especially Theory of Constraints, still barely known in France, will be part of my assignments and not only an opportunistic support to Lean and Six Sigma. All three approaches or methodologies combined as TLS synergy are on the ‘regular menu’.

I wish all of you to find your own reasons to get passionate and celebrate successes in 2015!

Theory of Constraints is something great, except for its name

Theory of Constraints (ToC) is among the three philosophies / approaches / methodologies with Lean and Six Sigma leading to tremendous success, but the only one with two frightening words out of the three of its name!

When facing tough challenge or stuck in a crisis, the last thing anyone would look for is a theory. Instead, people with urgent need for improvement would seek something practical, action-focused and yielding short-term.

Too bad, maybe the only thing that could help in such a case is named “Theory”.

>lisez cet article en français

The same people firefighting with their daily problems feel having more than their share of constraints and again, maybe the only thing that could help them holds “constraints” in its name.

I don’t know what led Eli Goldratt, father of ToC name it that name, but I am quite sure it is an obstacle (a kind of constraint!) to the diffusion and adoption of his teachings.

Fame, despite the name

The problem is that Theory of Constraints is now relatively famous, at least among all those having read ‘the Goal’ and grew a corpus which make a change of name unthinkable.

The same happened with ‘5S’, made of five Japanese words few westerners remember. They keep irritating, but it’s a bad idea to rename them if you want to remain understandable by others.

Same with ‘Lean’, first thought to be a clever way to summarize frugality in operations, but this name got mean meaning over time, with a meaning closer to anorexia thanks to poorly and ill-led implementations. Yet it is too late to change the name.

Newcomers, don’t get frightened by the name!

Newcomers give it a try! Don’t get frightened by the name, Theory of Constraints (ToC) is something great, except for its name, we’ll agree.

Think about much more frightening (and unpronounceable) names of drugs you take and the cure they provide. ToC is like such a remedy, not very good sounding but effective and with only positive side effects!

More on this subject: Bill Dettmer and Philip Marris discuss the point

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What is TLS? The Synergy of ToC, Lean and SixSigma


Chris HOHMANN – Author

TLS stands for Theory of Constraints, Lean and Six Sigma. TLS is meant to be the combination of 2 or all of these…philosophies, approaches, methodologies, you name them.

I discovered Lean (but we didn’t call it Lean then) and Theory of Constraints at the same time, when I joined a Yamaha Corp. subsidiary in 1989. Even so I gathered more experience with Lean, I used ToC principles and rules when relevant. Six Sigma came later but without surprise as I had been extensively trained about Statistical Process Control (SPC) long before Six Sigma gave it a new shine.

I used TLS without knowing it and came across concept and acronym only in the 2010s while reading Reza PIRASTEH and Kimberly FARAH’s paper “The top elements of TOC, lean, and six sigma(TLS) make beautiful music together” ( May 2006, APICS Magazine) and Bob SPROULL’s “The Ultimate Improvement Cycle” (CRC Press, 2009).

My “discovery” of TLS was nothing more than conceptualization and confirmation of what I have experienced by myself and found natural: using what the three components of TLS had to offer as a powerful synergy.

Introduction to TLS

This slide show provided by Philip MARRIS, CEO of Marris Consulting will give you an introduction to TLS.


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Approach, philosophy or methodology?


Chris HOHMANN – Author

We hear and read them often in relation with our preferred body of knowledge*, among which Theory of Constraints, Lean and Six Sigma are the most popular: the terms “approach”, “philosophy” and “methodology”.

I wonder if people use them purposely or as synonyms and I prick up my ears each time an expert explains Theory of Constraints (ToC), Lean and Six Sigma is not this or not that.

Paying utmost attention to the sense of words, especially in English which isn’t my mother tongue, I decided to make some research of my own about what is what and when to use it.

A chose the Macmillan online dictionary and found this:

  • Approach (noun): a particular way of thinking about or dealing with something
  • Philosophy: a system of beliefs that influences someone’s decisions and behaviour. A belief or attitude that someone uses for dealing with life in general
  • Methodology: the methods and principles used for doing a particular kind of work, especially scientific or academic research

No surprise, these terms are not synonyms. Yet there is a certain relationship that I see as concentric circles:

Philosophy as a system of beliefs and knowledge provides a global influential framework. Approach is a focused way to deal with something, largely influenced by the philosophy. Consistently, the proper Methodology helps Approach dealing with something by providing methods and tools.

Philosophy is more about abstraction and knowledge, thinking and attitude while Methodology is action focused. Approach is somewhat in between and links Philosophy to methods and tools, or thinking and attitude to doing and action, if you will.

Fine, so what are ToC, Lean and Six Sigma for example?

Well, for me first they are systems of beliefs backed by tangible proofs and knowledge. They influence my way of thinking and consider things. When I have to deal with a situation, an issue, I am influenced by this system and it formats they way I will approach it. Of course I will use the methods and tools ToC, Lean and Six Sigma provide in a certain way**, which is my approach.

**Using ToC, Lean and Six Sigma in combination or synergy is referred to as “TLS

So to answer the question what are ToC, Lean and Six Sigma, my answer is they are what you make them! They can be either Philosophy, Approach or Methodology or a combination of the three.
Therefore, in my opinion, nobody is wrong using any of these words as qualifiers, but the choice should be made with care for the sake of clarity.

Assuming only few people really pay attention to the meaning of the words, I think most people use them alternatively as synonyms. I dare ask what they mean if I feel necessary to clarify.

Adding to the confusion with Body of Knowledge and Paradigm

Sometimes we also come across Body of Knowledge and Paradigm. What do these words mean?

A *body of knowledge (BOK or BoK) is the complete set of concepts, terms and activities that make up a professional domain (
BoK is shared and accepted by a community while a philosophy can remain personal.

Paradigm is a formal set of ideas that are used for understanding or explaining something, especially in a particular subject. It is a windows through which watch things or a prism through which seeing and understanding something.

“Prism” is purposely chosen as the point of view can be biased or distorted.

Best example is probably the world of cost paradigm vs. world of throughput paradigm, where the proponents of the second see the biases of the cost paradigm.

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7 Quality Control Tools

They are known since heyday of Total Quality Management in the 1970s and they are still used and useful today: the seven quality control tools.

These tools have been selected to give shopfloor workers means to control, analyse and improve quality based on facts and objective data. The tools are simple enough to be used with minimum algebra.

The seven quality control tools are:

  1. Graphs
  2. Check Sheets
  3. Pareto Chart
  4. Cause & Effect diagram
  5. Scatter Diagram
  6. Histogram
  7. Control Chart

Their order may vary from one author to another but order is not that important.

Here is a 8mn video listing the 7 quality control tools provided by Gemba academy

What is Six Sigma?

Beside Lean, Six Sigma counts among the most popular performance improvement approaches. Based (and named) upon statistical data and tools, Six Sigma’s aim is to speak with data and facts. It is the most “scientific” methodology in the Theory of ConstraintsLean – Six Sigma (TLS) trio.

Once thought to replace Lean, Six Sigma rather completes it. Despite a certain overlap, many comparisons try to clearly discriminate what is in the Lean and what in the Six Sigma pigeon holes. The following presentation is a nice summary for both Lean and Six Sigma.