Lean Vs Six Sigma

Opinions abound...Lean and Sigma both address the areas you mentioned....In my opinion, the true difference is found in the fact that sigma uses the scientific method to create new knowledge about a process where it did not exist before ...Lean takes existing knowledge and uses it to drive waste out the process as defined by your customer.  Just like an athlete training for competition, the first step is to get the fat off em (lean), the second step is to get them to perform to some standard (sigma)...most experienced practicioners of sigma inherently include lean elements into their CI efforts simultaneously, and the line between the two becomes blurred.

the difference is the following, SS focuses on reduction in variation or effectiveness.  Lean focuses primarily on efficiency.  Both of these methodologies offer a lot of synergizes and therefore often you will hear the term Lean Six Sigma.

Hi,

my two cents:

SS will focus on the parts of a process that add value in order to optimize them. Lean will focus on the parts of the process that do not add value in order to eliminate them.

Regards

Sandor

Hi,

My favorite topic..

Both the methodologies start from different focal points with same objective.

	Lean	Six Sigma
Approach	Remove waste in process to improve velocity	Reduce variation in process to improve quality
Method	Kaizen,Kaikakku (Rapid Kaizen). These are more flexible	DMAIC, DMEDI, DMADV etc. Thse are more structured
Focus	Quality	Flow
Primary Goal	Uniform Process Output	Reduced Flow Time
Secondary Goals	Reduce Inventory	Less variation
	Reduce Lead time	uniform output
	Reduce Waste	Improved quality
Why they need each other ( Short comings)	Focusses on Single Process, improved processes may not affect entire value stream	Does not look at Statistics or individual system analysis in depth
	More rigid due to strict project approval processes	no structured deployment& learning infrastructure (i.e no GB,MB,champion etc.)
	People & Partners improvement not explicitly mentioned	Does not recogonize variation

As mentioned above both needs each other to perform effectively.

For example An improved SS Process may have three steps with FTY 0.99,0.99,0.99

The RTY will be 0.97

If you apply lean(VSM) and find that process #2 is not required & you eliminate it.

Then the RTY will imprve automatically to 0.98

I hope it is ok.

Thanks & Bye,

Senthil

	Lean	Six Sigma
Approach	Remove waste in process to improve velocity	Reduce variation in process to improve quality
Method	Kaizen,Kaikakku (Rapid Kaizen). These are more flexible	DMAIC, DMEDI, DMADV etc. Thse are more structured
Focus	Quality	Flow
Primary Goal	Uniform Process Output	Reduced Flow Time
Secondary Goals	Reduce Inventory	Less variation
	Reduce Lead time	uniform output
	Reduce Waste	Improved quality
Why they need each other ( Short comings)	Does not look at Statistics or individual system analysis in depth	Focusses on Single Process, improved processes may not affect entire value stream
	no structured deployment& learning infrastructure (i.e no GB,MB,champion etc.)	More rigid due to strict project approval processes
	Does not recogonize variation	People & Partners improvement not explicitly mentioned

There was a problem in pasting ( SS & Lean interchanged) . I'm very sorry.

Thanks & Regards,

Senthil

Well, theoratically, SS is for reducing variation and lean is for improving average performance of any given process, but you need to consider how they were applied in your process improvement iniatives.

I looked through various organizations and they all used them in different meanings for different purposes.  Also in many cases, a goal of iniatiaves is both of improving average business performance and reducing variations.

Hope this help you out ....

SS reduces the vartiation in you process (when used correctly)

 

Lean-

1.id's/reduces muda (va vs nva)

2. creats flow

The other posts are good, but this is how I sum it up to management and non-technical people.

Six Sigma - Variation Killer

Lean Thinking - Waste Killer

Makes a good poster

Jobby Johnson, CSSBB

Secretary, Lean Enterprise Forum

This is my perspective on lean and six sigma...

Lean deals with being effective (in other words doing the "right" things) what is meant by this is distinguishing value-from non-value added portions of your process. Lean philosophy centers itself on understanding and identifying waste then onto pull, flow and continuous improvement. Eliminate waste and non-value added processes...and focus on only the "right" things.

Six sigma deals with being efficient ( in other words doing things "right") understanding the Critical to Customer (Quality) measures of your value added processes, defining target and control limit values then striving for lowering process variation to where you have process capability to a six sigma level (3.4 defects per million opportunities).

Looking at Lean Six Sima in this manner- makes the most sense to me- The lean perspective comes first then on to applications of Six Sigma-

Unless you have "Leaned out" your processes you may be trying to make six sigma capability of processes that are non-value added and wasteful in the first place...

Ron B.

Lean is focused on velocity Six Sigma is focused on variaiton reduction. You need them both to be effective

All, First of all, thanks to everyone for their perspectives. From all the posting, I have come to the conclusion that: Lean = A less disciplined, quicker, "ATTACK" it approach, focused on removing wasteful operations in a process, moving the average output. It is implied that customer satisfaction will improve. Six Sigma = Disciplined, slower approach, focused on improving customer (internal or external) experienced defect levels, by reducing variation and/or shifting the mean.

The choice of which to implement seems to be more of a match against the "culture" of your organization, vs. validity of methodology. But, if the focus is to drive profit by both driving Sales higher and Cost lower, the explicit connection of Six Sigma to Customer's expectations seems to give it an advantage.

Speed/Flow vs. Variation of Processes is just one difference and relationship.

An exammple how these two are connected: if there is too much variation in processes including equipment failures, things can not flow consistently to the customer demand pace. The end result is that in order to meet deliveries, one would increase WIP and inventory and batch, right back where Lean is intended to get you away from. I personally have not know any value stream mapping that incorporates the variability of processes and consider its impact. Therefore a Lean process is very sensitive to variations, but also exposes the sin of variation which creates waste. I have seen examples of Lean languishing and backtracking or hitting a ceiling for this reason.

Six Sigma a nonlean and compliacted process is just not smart. Six Sigma, while it definitely address it, typically does not approach a process design and improvement from the flow and velocity and waste perspective with the same vigor and focus and tools as Lean.

Minimum variation creates a condition where maximum Lean power and benifits could be attained. Lean processes also removes opportunties for variation, such as removing a process step altogether. There goes any variation associated with that step.

There are other differences and connections between the two.

Regards,

Hong

The REAL power of Six Sigma is in the predictive equation Y=f(x). The output of a process is a function of a few critical inputs. Manage the inputs to control the output. Also, value stream mapping is great tool to deploy system-wide Lean and Six Sigma.

I disagree about Lean being less disciplined - Lean requires that the entire organization adopt discipline

By disciplined, I was refering to the rigor emphasized in the tool usage. Not about the practioner or the organization.

Boy, I must be an old time thinker.  I remember all the times when we used the Six Sigma methodology to reduce cycle times.  Why do people worry about Lean vs Six Sigma labels?

I agree. I think our basic toolbox has evolved to the point where VSM can essentially be included as part of the process mapping excercise. This not only includes what is to be done at a particular point , but looks at the potential sources of waste at that point also.

For all those  good  reasons  I'm  taking  the Lean-SS Course  ,organized  by  VillanovaU.

Hi,

To add to the discussions on why we have to use Lean & SS in tandem is this example (I have repeated the same from my earlier post).

Assume you are having a True Six Sigma Process with 5steps with Yields

Step 1 : 0.9999966 DPMO : 3.4

Step 2: 0.9999966 

Step 3: 0.9999966

Step 4: 0.9999966

Step 5: 0.9999966

Your RTY is 0.97 ( product of Yields) & DPMO is 17.00.

By using Lean methodology you find that Step 2,Step 4 & Step 5 are waste and can be eliminted.

Then your RTY  is  6.8 since you have reduced your oppurtunities to create a defect.

Regards,

Senthil

Hi,

To add to the discussions on why we have to use Lean & SS in tandem is this example (I have repeated the same from my earlier post).

Assume you are having a True Six Sigma Process with 5steps with Yields

Step 1 : 0.9999966 DPMO : 3.4

Step 2: 0.9999966 

Step 3: 0.9999966

Step 4: 0.9999966

Step 5: 0.9999966

Your RTY is 0.97 ( product of Yields) & DPMO is 17.00.

By using Lean methodology you find that Step 2,Step 4 & Step 5 are waste and can be eliminted.

Then your RTY  is  6.8 since you have reduced your oppurtunities to create a defect.

Regards,

Senthil

Senthil,

Am I missing something? I calculate the RTY for the 5 step process to be 0.99998 (not 0.97 as stated).

I get your rather hypothetical point, but I don't think that the (revised) numbers would make a very convincing argument.

Hi,

I have attached the excel sheet on which I have made the calculation.

Parameters		Before	After
FTY	Step 1	0.999997	0.999997
	Step 2	0.999997	1
	Step 3	0.999997	0.999997
	Step 4	0.999997	1
	Step 5	0.999997	1
RTY		0.999983	0.999993
Yn		0.999997	0.999999
Process DPMO		17.00	6.80
Note: For removed processes oppurtunity is 0 hence FTY = 1

This is not an hypothetical case, only I have given an example from on of our project experience ( Though  I have changed the same for purpose of simplicity & clarity).

Even as a mathametical approach if you see the same will be valid.

Please do not think that I am arguing on your feedback, I am explainning the thing again just not to create a miscommunication to the forum. I value your feedback and take this feedback as a reflection of my bad explanation in my previous mail.

Thanks & Regards,

Senthil

Hi Folks,

I Disagree . Six Sigma begins with mapping the existing process and next step is to identify the value adding and NVA activities. And if you are able to identify NVA's , what are you waiting for..Eliminate them.

In short , I believe Six Sigma is capable of identifying as well as eiminating NVA's. Any fresh thought(s) would be highly appeciated.

Hi all,

I accept MKS's view , SS includes the step VA & NVA identification.

But the difference is in how it is used in actual.

In actual many cases the "Process" is mapped and not the "Value Stream".

In effect it is the "Point Velocity" that will be increased.

What is beneficial for the customer is an increased "Stream Velocity" & not the " Point Velocity".

Can we be frank in telling the forum in how many SS projects we map the value stream & improve the pace of the complete Value Stream.

Please post your opinions/experiences.

Regards,

Senthil