I agree with Jim. Let's not go there again. Serves no purpose and it is a too much emotionally and politically loaded subject.
Stijloor.
I agree with Jim. Let's not go there again. Serves no purpose and it is a too much emotionally and politically loaded subject.
Stijloor.
C
chubar
Hello Everybody there....A very Good Day to all of you. I am extreamly happy and proud of having such a forum and intelligent people.
I am very new to six sigma. I am working in a IT company which is supply chain distributor and no.1 IT distributor in middle eat and Africa region. We have many service centers too. I am into finance, at present in service business and going forward will look distribution aswell as sales.Can anybody help me how to start and where to start Six sigma....
I am very much confused with the graph showing usl and lsl...i really have doubt why this upper limit and lower limit is fixed and actuallt what does it mean. Can anyone help me to clear my doubt.
Many thanks,
Best Regards,
Subash
I am very new to six sigma. I am working in a IT company which is supply chain distributor and no.1 IT distributor in middle eat and Africa region. We have many service centers too. I am into finance, at present in service business and going forward will look distribution aswell as sales.Can anybody help me how to start and where to start Six sigma....
I am very much confused with the graph showing usl and lsl...i really have doubt why this upper limit and lower limit is fixed and actuallt what does it mean. Can anyone help me to clear my doubt.
Many thanks,
Best Regards,
Subash
C
chubar
Hello Everbody there..Good Day..Very happy to see intelligent people in this forum. I am working into an IT company which is involved into sales, distribution and service. At present i am into service and working as an asst manager-Finance.
I am very much interested in Six sigma...but have a big doubt about the USL and LSL. Can somebody explain me why these limits are fixed and why they are relevant to Six sigma.
Thanks,
Best Regards,
Subash
I am very much interested in Six sigma...but have a big doubt about the USL and LSL. Can somebody explain me why these limits are fixed and why they are relevant to Six sigma.
Thanks,
Best Regards,
Subash
A
artichoke
Subash,
The Upper and Lower Spec Limits can be anywhere you like ... 4 sigma, 6 sigma, 12 sigma. They are set by the manufacturer and/or customer, not by the process. The number of defects can hence be any level you want, depending on where the spec limits have been set. Defects are a very poor measure of quality.
Six Sigma's metric of 3.4 defects is based on utter nonsense, as described in my published papers:
http://www.qualitydigest.com/inside/six-sigma-article/six-sigma-lessons-deming-part-1
http://www.qualitydigest.com/inside/six-sigma-article/six-sigma-lessons-deming-part-2
I also suggest reading Deming's book "Out of the Crisis" ... particularly relevant today given the current economic crisis.
The Upper and Lower Spec Limits can be anywhere you like ... 4 sigma, 6 sigma, 12 sigma. They are set by the manufacturer and/or customer, not by the process. The number of defects can hence be any level you want, depending on where the spec limits have been set. Defects are a very poor measure of quality.
Six Sigma's metric of 3.4 defects is based on utter nonsense, as described in my published papers:
http://www.qualitydigest.com/inside/six-sigma-article/six-sigma-lessons-deming-part-1
http://www.qualitydigest.com/inside/six-sigma-article/six-sigma-lessons-deming-part-2
I also suggest reading Deming's book "Out of the Crisis" ... particularly relevant today given the current economic crisis.
G
Geoff Withnell
I fully agree with 3.4 dmo as being silly, but USL and LSL CANNOT legitimately be set anywhere you like. Specifications should be set by "voice of the design". What are the design requirements.
Geoff Withnell
Geoff Withnell
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artichoke
"Another way to improve the yield is to increase the design specification width" Mr Bill Smith, IEEE Spectrum 1993.
Your design can be whatever you want ... hence so can your specs. Your customer may have different specs for your product and may choose to change them. In other words, spec limits are not set in concrete.
Conversely, you have no control over natural process limits other than by improving the process. What the process is doing is the true indicator of quality.
The Shewhart control chart is the best indicator of quality. It is relevant for the majority of processes, regardless of data distribution. Six Sigma's metrics are next to useless as a measure of quality.
Artichoke - you and I have been thru this before - you are misrepresenting what Bill Smith actually proposed. This is a real shame as he actually proposed what Geoff is saying, but most people would never know that as his two published papers are hard to obtain. defaming a dead man is a bit impolite wouldn't you agree?
in my opinion and experience I don't believe that control charts are the best indicator of quality. that's not to say that they aren't useful - they are: in the main, they are the best way of determining if a process is in statistical control and stable, provided of course the correct chart is chosen for the process at hand. However, they don't by themselves indicate quality levels. That has to do with the process behavior in relationship to the true requirements - as defined explicitly or implicitly by the Customer. Although the control chart can indicate decreasing or increasing process variation it isn't the only tool that can do that. Additionally not all features provide more value thru endless reduction of variation.
in my opinion and experience I don't believe that control charts are the best indicator of quality. that's not to say that they aren't useful - they are: in the main, they are the best way of determining if a process is in statistical control and stable, provided of course the correct chart is chosen for the process at hand. However, they don't by themselves indicate quality levels. That has to do with the process behavior in relationship to the true requirements - as defined explicitly or implicitly by the Customer. Although the control chart can indicate decreasing or increasing process variation it isn't the only tool that can do that. Additionally not all features provide more value thru endless reduction of variation.
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G
Geoff Withnell
Oh come now! No reasonable person, and certainly not Bill Smith believes (or believed) that you can design whatever you want. There is is concept called the real world and natural laws, which limit what will work in the design and therefor what the spec limits are.
The best indicator of quality is the customer results! Everything else is an estimated prediction of the customer results.
Geoff Withnell
FWIW... this quotation was not made by Bill Smith. It was in the article by Bill Smith, but author listed as Linda Geppert.
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artichoke
Read my post. I quoted a dead man. A quotation is not defamation.
I am not surprised that you feel this quotation from Bill Smith's paper is "defamatory". I have encountered many people who disbelieve the quotation because they find it an embarrassment. The truth hurts at times. His paper is not "hard to obtain". Buy it from IEEE.
I am however, often tempted to comment on those stupid enough to follow the Six Sigma nonsense.
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