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What is the conversion for PPM defects vs. Sigma Equivalents?

Statistical Steven

Statistician
Staff member
Super Moderator
#21
Bev D said:
and your point is? if it works who cares what you call it? I am seeing real statistical engineering quality improvements and control being enacted in numerous organizations under the name of six sigma that I never saw under process control or tqm...i'm just thrilled more people and organizations are actually using and embracing the techniques and systematically ingraining them into their organizations...I just dont get the visceral disdain around the term (seemingly bitter?)


I understand the disdain for the hacks (like Mikel Harry) who used good old american capitilism or snake oil salesmanship and made tons of money off the name gimmick - but these guys are always out there.
Bev, let me give you my $0.02 as to why six sigma is a sham. Call it bitter, because I am. I spent nearly 20 years as a professional statistician, CQE and quality improvement professional just to be told I am not qualified to be a six sigma black belt. I need to be blessed by some money making organization to learn tools I already have? I guess I just do not get it.
 
E

e006823

#22
Bev D said:
and your point is? if it works who cares what you call it? I am seeing real statistical engineering quality improvements and control being enacted in numerous organizations under the name of six sigma that I never saw under process control or tqm...i'm just thrilled more people and organizations are actually using and embracing the techniques and systematically ingraining them into their organizations...I just dont get the visceral disdain around the term (seemingly bitter?)


I understand the disdain for the hacks (like Mikel Harry) who used good old american capitilism or snake oil salesmanship and made tons of money off the name gimmick - but these guys are always out there.

Mikel Harry is a very divisive character with 6 Sigma practitioners. In my opinion his most significant contribution was the marketing of 6 Sigma. It gave the techniques credibility in the boardrooms due to the emphasis on savings and the bottom line.
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#23
Statistical Steven said:
I spent nearly 20 years as a professional statistician, CQE and quality improvement professional just to be told I am not qualified to be a six sigma black belt. I need to be blessed by some money making organization to learn tools I already have? I guess I just do not get it.
Now that's a great answer! And I've been there. Back in the mid nineties I was 'doing' six sigma for Honda (although I didn't call it that because Honda likes to do their own thing). I started applying for master balck belt positions since I had a very strong training background and improvement project leadership/success rate. I was told by everyone that since I wasn't 'certified' by GE or Allied or Motorola then I wasn't qualified to be a MBB.. so I bit the bullet, held my nose and went to one of those 3 companies to become certified as a BB...worst 18 months of my life. their program was Mikel Harry joke right down to the powerpoint clip art handouts and the 1.5 sigma shift. As soon as I got thruthe program I was out of there. but I had my golden pass and my career took off in the direction I wanted it to.

But there always these types of artificial barriers - form teh 'need' for a certain 4 year degree to a speicifc experience, etc. the trick is how you manipulate around this and sell your experience and success as meetign and even exceeding the 'piece of paper'...
 
G

Gerula

#24
?

Hi everybody,

You might say anything you want about Mikel Harry (at the end of the day it's a matter of personal opinion) only that we have to keep in mind that usually a business is run to make profit. From this perspective, what Mikel did was to convince the owners/CEOs/CFOs and so on to start using inteligent tools when running their operations in a structured manner. Is he a salesman? Yes, he is. Is he taking advantage of this system? Yes, he is. But isn't this our society is all about? Yourselfs have said that you tried to sell your knowledge and you couldn't due to various reasons including not being a certified BB (to be honest, why a certification as QE is different than a BB? Both are commercial certification as you have to pay for and other than a certification body saying that you passed their certification criteria there is no guarantee of how the individual is going to perform in real life- wait a minute isn't this what school does too?). So, beyond the phylosophical discussions, as long as a system works it's up to the practitioneer to use those tools that are most suitable to the business they are part of. Do I sound too much like a cold bloded finance-ist? Yes, but take a look around you and see how the world functions lately, look at how many jobs are being lost to low cost countries. Is this a good time to polemize about systems and implementation methods and who makes money out of that? I say let's go back to discussing professional subjects and see how we can help each other progress in what we do every day.

Regards
 
R

ralphsulser

#25
Bev D said:
Now that's a great answer! And I've been there. Back in the mid nineties I was 'doing' six sigma for Honda (although I didn't call it that because Honda likes to do their own thing). I started applying for master balck belt positions since I had a very strong training background and improvement project leadership/success rate. I was told by everyone that since I wasn't 'certified' by GE or Allied or Motorola then I wasn't qualified to be a MBB.. so I bit the bullet, held my nose and went to one of those 3 companies to become certified as a BB...worst 18 months of my life. their program was Mikel Harry joke right down to the powerpoint clip art handouts and the 1.5 sigma shift. As soon as I got thruthe program I was out of there. but I had my golden pass and my career took off in the direction I wanted it to.

But there always these types of artificial barriers - form teh 'need' for a certain 4 year degree to a speicifc experience, etc. the trick is how you manipulate around this and sell your experience and success as meetign and even exceeding the 'piece of paper'...

:applause: Good for you Bev, I agree.
 
N

Narfeldt - 2011

#26
PPM vs Sigma level

I found a formula that I entered in excel.
You can see the formula in column B.
Hope this could help you.
 

Attachments

Tim Folkerts

Super Moderator
#27
Narfeldt,

That's a rather good approximation for converting between sigma levels and PPM. It seems to be good to within about 2% over the range of 2 sigma to 6 sigma.

Still, why not just use the "true" conversion?

=(1-NORMSDIST(A2-1.5))*1000000

Granted, calculators often don't have the inverse normal function built in, so then your equation

=EXP(-((A2-0.8406)^2-29.37)/2.221)

would be a handy alternative. But since Excel (and many other similar programs) can do the true function, we might as well use it there. The true version also lets you remove the 1.5 sigma shift if you so desire.


Tim F
 
P

Palt88

#28
Dear all, sorry to "undig" the post, but I have a little concern with some values.

Does someone is able to give me the real conversion of 4 sigma to Ppm? (with no 1.5sigma shift)

You will tell me "you already have an exemple upside".
The problem is that if we took this table:




ok 4 sigma gives 96ppm...

If I check another table:





ok...63ppm....


My statistical software gives me a 4 sigma up to little bit more than 32ppm.

My statistical software gives value with no 1.5 sigma shift, means that I found 4.5 sigma with 3.4ppm.

The 2 tables above gives 2700ppm for 3 sigma, as ma statistical software gives 1370ppm.

Then you can see for 2 sigma the 2 tables are different, 71860ppm - 45500ppm and around 23000ppm for my software...

:confused:

How to clarify that? it seems that for the 4.5 sigma at 3.4ppm everybody is ok, but do someone is able to explain why we can find so different things for other values?

Thanks
 

Tim Folkerts

Super Moderator
#29
The "traditional" calculation assumes teh process is centered and included both tails. The six sigma calculation assumes the process is shifted to one side, so it only includes the closer tail.

If you double the results you calculated, you will get the "traditional" result.

And it looks like the "96" value for 4 sigma is wrong -- it should be 63. I get 31.7 PPM for each tail, or 63.4 PPM for both tails.


Tim F
 
P

Palt88

#30
Thanks tim. :agree1:

I still have a doubt... because the result I got (32ppm) is the "Total ppm", as the addition of ppm on both side...
Would I really need to x2 the result from my statistical program?
 
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