# lin

## Forum Replies Created

Viewing 100 posts - 1 through 100 (of 267 total)
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• #188571

lin
Participant

Not a dumb question for some. Some people like to know the history of things – about 25% of the population wants to know the history. It is like asking for the history of Six Sigma. Where did it come from? Why did it work in the past? Does what happened in the past imply it will work in the future? He asked a simple question. If you don’t know the answer, then don’t answer. So simple. But, I see from this forum that does not stop you.

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#188535

lin
Participant

Hello Jorge,
You know not what you just did. Let the fireworks begin.

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#188099

lin
Participant

Let’s try that code again:Function d2cal(n)Dim StartNum As Long, EndNum As Long, NumPoints As Long, Dx As DoubleDim Int1 As Double, Int2 As Double, i As Long StartNum = -200 EndNum = 200 NumPoints = 1000 Dx = (EndNum – StartNum) / NumPoints Int1 = 1 – (1 – Application.NormSDist(StartNum)) ^ n – (Application.NormSDist(StartNum)) ^ n For i = 1 To (NumPoints – 1) Int2 = 1 – (1 – Application.NormSDist(StartNum + (Dx * i))) ^ n – (Application.NormSDist(StartNum + (Dx * i))) ^ n Int1 = Int1 + 2 * Int2
Next i Int2 = 1 – (1 – Application.NormSDist(EndNum)) ^ n – (Application.NormSDist(EndNum)) ^ n Int1 = Int1 + Int2 d2cal = (Dx / 2) * Int1End Function

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#186372

lin
Participant

Hello,
I read your article in your continuing debate with Dr. Wheeler. In your real data example, you say:”The example data used in this discussion is a true enterprise view of a business process. This reports the time to change from one product to another on a process line. It includes six months of data from 14 process lines that involved three different types of changeouts, all from a single factory. The factory is consistently managed to rotate through the complete product line as needed to replenish stock as it is purchased by the customers. The corporate leadership considers this process to be predictable enough, as it is run today, to manage a relatively small finished goods inventory. With this process knowledge, what is the optimal method to report the process behavior with a chart?Figure 1 is an individuals chart of changeover time. From this control chart, which has no transformation as Wheeler suggests, nine incidents are noted that should have been investigated in real time. In addition, one would conclude that this process is not stable or is out of control.”Do I understand you correctly that you used data from 14 lines and three different change outs on the same chart? Isn’t that kind of mixing apples and oranges? I don’t think I would put three different types of changeouts on the same individuals chart.It might be interesting if you provide the actual data and show the context in which it was taken including process, type of changeover, etc. Are 9 out of control points (with over 500 data points)due one type of changeout? I can’t tell based on our article.Regardless, interesting reading.Bill

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#184962

lin
Participant

Not for me.  My pages still take 10-15 sec to load.  Very slow response.  Not that anyone cares, but I think I’ll just go play somewhere else.

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#184951

lin
Participant

Andy: Sometime back you pointed out that most things were topsy-turvy – you are right. Thanks for trying to wake us up. Regretably, the sleeping giant is still asleep.Bill

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#182421

lin
Participant

Can you send me the simulation? Thanks.Bill
sampsonwd2007@yahoo.com

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#182178

lin
Participant

No, not a book question.  I’m trying to apply this as a way to compare destructive testing methods at different manufacturing sites.  I have multiple moisture analyzers that I need to compare.

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#182086

lin
Participant

Robert,
Thanks for the reply.  WHat I’m specifically trying to do is use a simple one-way ANOVA to show equivalence.  It’s relatively easy to choose the “zone of indeifference” in a 2 sample equivalence test, since this is a pretty intuitive thing.  For example, if I want to prove equivalence between the strength of two different materials, I would say “if the sample averages are within 10% of each other, this is equivalent for my purposes”.  Then I would do two one-sided tests to confirm that the lower and upper confidence limits are contained within the +/- 10% zone.
THe problem with doing this with ANOVA is that the “zone of indifference” is no longer expressed in the original units of measurement, but in the ratio of the variances (F-score).  I just can’t seem to make the logical leap that makes this intuitve.  For example, I could say “the zone of indifference (equivalence of multiple samples) is when the F-score is less than 2”.  This would be a hard limit that you could then select appropriate sample sizes to achieve, then test against.  But expressing equivalence in terms of an F-score is just not intuitive – to me at least.
Clear as mud?

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#181872

lin
Participant

You are wrong.
3 sigma is only used by that crazy Shewhart – Deming – Wheeler crowd.
In the highly acclaimed and incredibly brilliant Six Sigma, we only use control charts with 6 sigma limits.  The psychologist Mikel Harry has proven it to be true.

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#178327

lin
Participant

I disagree on using the p control chart.  The probability of attrition is not the same for all employees.  For example, younger employees tend to switch jobs more often.  Thus, one basic condition for using the binomial distribution for the control limits in the p chart is not met.
I would use an individuals control chart.

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#178175

lin
Participant

Here it is free down load for cqe exam
http://iqualityengineer.com/certified%20quality%20engineer%20bok.html
Good luck

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#177784

lin
Participant

Hi Stan,
Can you help? Where is this open source & QCI material?
I am new to the site.
Thanks!

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#173120

lin
Participant

Why do you want to use a subgroup size greater than 25?

Bill

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#61999

lin
Participant

Michael, I am interested in knowing more about those benchmarks from GE.  Could you email your contact information?  My email address is btoujouse@ejgh.org.
Thanks, Bill

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#171906

lin
Participant

Kris, good question, more subtle than some realize, Robert and BC have provided the basic math.  Remember that if the slope is not statistically signficantly different from zero, then there is not a significant correlation between the x’s and y’s.  The algebra provided by BC and Robert make that clear, as b –> 0, r^2 –> 0 too.

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#171337

lin
Participant

If z = 1.85:
The area under the curve to the left of z = 1.85 is found using the following in Excel:
normsdist(1.85) = 0.968
You can also use: normdist(1.85, 0, 1, true) which is for the normal curve wiht average of 0 and standar devation of 1.
For the area under to the curve to the right of z = 1.85 simply use:
1-normsdist(1.85) = 0.032
I don’t know where you get your 0.4678 result.
Bill

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#170973

lin
Participant

Just a quick add to RhinoNeil’s response.     Several recent articles have been published regarding the iSSSM six sigma maturity model.    Easiest place I know to find it is at the Instantis home page or perhaps ISSSP website.     Our team has been wrestling with a similar question and has recently begun work to integrate the iSSSM maturity model, Michael Hammer’s Process Audit (Harvard Business Review) and a set of lean maturity criteria (Shingo).    Our objective is to create a self assessment tool that; (1) helps support our longer term vision of excellence and (2) provides a gap analysis that will then become an input to the planning process.

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#167694

lin
Participant

As a motivational speaker and someone with a lot of credibility in the manufacturing field, Mario Perez Wilson is probably the best.

We used another famous individual first, and it was a disaster. Then, an ex-Motorolan recommended we contact Mario and it was unbelievable.

Our Six Sigma program runs flawless. We hired his consulting firm to proceed with the whole training and deployment.

My company is in Massachusetts we are in manufacturing. Our program got delayed by 6 months for picking the wrong person the first time.

He has two websites http://www.perez-wilson.com and http://www.mpcps.com

Good luck.

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#167581

lin
Participant

What about Six Sigma in the blow-molding industry?  Have you learned anything interesting about that?   You’re not still giving away extra plastic for free are you?

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#166976

lin
Participant

Samyukta,
Why pay for training if you already understand the methodology?   You could become GB certified through ASQ – though you might need to find a good Lean Six Sigma text and brush up.  Good luck!

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#166573

lin
Participant

Robert,
What is the best way to contact you?
Regards,
Bill

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#165947

lin
Participant

I guess my first post didn’t really pertain to the original title of this thread, but then a lot of the posts are likewise guilty.
I have to agree with Brandon. No quality system can overcome people issues, only management can shoulder that load when people are not capable or willing to give their best effort.
I also have to agree with Six Sigma Shooter, mangement is mostly interested in short term performance. Many CEOs, etc. only care about their bonus or golden parachute that their cronies (since they all sit on each others’ boards) grant them. Providing the resources (ISO requirements be damned!!!) to provide excellent customer service or any other long term improvement just isn’t on their personal agenda.
Many companies hire fresh faces out of college to mid level management positions that just don’t have the experience to be effective.
Finally, even many posters to this thread, well intentioned as they may be, can’t even agree among themselves about what quality should be. It doesn’t seem to matter to me what “method” one selects as long as you get where you are going. Instead of debating flavor of the week, we should figure out how to convince and educate the masses. Many of the “problems” that are posted would disappear if more people up and down the chain of command were quality practitioners.

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#165884

lin
Participant

I am new to SS, went through TQM, ISO, etc.
Question is, with all this quality going around, why are most companies so poorly managed and why does most customer service stink?

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#59207

lin
Participant

What are you refering to when you say “contact rates”?

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#61769

lin
Participant

I would be curious too.  I am a new black belt and would like to be more involved here at this hospital.
Bill

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#61768

lin
Participant

How does this book relate to healthcare?  I am curious.  How helpful is it?
Bill

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#61715

lin
Participant

What do you mean by Takt?  Our transcription is done by an outside vendor.  I am doing a labor production analysis now.  When you say TAT, do you mean from the time the exam is started to signed out?

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#61684

lin
Participant

I was not able to find anything other than the packet that is available to purchase for \$9.95.  Is there anything else out there, that anyone knows of?

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#61668

lin
Participant

I understand, but could some one give me some direction in getting started.  Where to find the data?  What data would be needed, etc.?
Thanks,
Bill

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#61660

lin
Participant

That would be a great help.  From what I understand, there has never been one done here before and the director would like to see one done, however, he is not sure of what he wants. But, any information to start one and to develop from there would be a good start.  Do you have an email where I can contact you?
Bill

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#159618

lin
Participant

If I have 10 million lines of software code, and each line of code needs to conform to 300 software itemized code standards, what are my opportunities for success?

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#159050

lin
Participant

Kris,
There are products which perform one of the functions listed, but I’m not aware of a product which does both.
For enterprise-level metrics and SPC, you could check out Hertzler Systems or PQ Systems (and there are others).
For project tracking, you could check out Power Steering, i-Solutions, Instantis, or Traction (and there are others).
Good luck.

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#158431

lin
Participant

If the annual recertification entails a fee, which is most certainly does, then it also has another name: ANNUITY.  Your instincts to be cynical are correct, in my opinion.  Sounds like a razor blade business model.

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#158430

lin
Participant

Jim,
Anybody who has ever done real work with a control chart knows that processes shift over time.  That’s not the point.  The idiocy of the “1.5 Shift” argument is the claim that it is anything other than a generalized fudge factor to use when long term instability is not understood.   Your prior post admitted seeing shifts ranging from 1.0 to 1.8.  So why use 1.5?  The whole concept is noise – a distraction best ignored since it has no bearing on the actions that must be taken to actually improve a process, in my opinion.

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#158090

lin
Participant

Yes, the courses are offered for credit, within the business school curriculum.  The “Masters Certificate” would be something else entirely, probably on a non-credit basis without enrolling in a degree basis.

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#158067

lin
Participant

I am aware of a couple of schools which offer Lean Six Sigma courses within their curriculum:
The University of Notre Dame, Mendoza College of Business, offers a Green Belt course within its MBA school.
The Ohio State University, Fisher School of Business, offers a Black Belt course within its MBA program, and a Green Belt course for undergraduate business students.  I understand that the Engineering school will be adding a Black Belt course at the undergraduate level this fall.
Cal Poly plans to launch a BB course in the Graduate School of Business this fall.
Cornell has offered a BB course in the MBA program.  I believe the instructors may be provided by Johnson & Johnson.
I hope this helps.

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#157587

lin
Participant

Thanks so much for sharing your knowledge.

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#157583

lin
Participant

Thanks Robert.   Two more questions: It appears to be the case as long as you look at the coded factors (-1 high, 1 low).  If I use actual values, I get strong correlations.  For example:

A
AB
B

0.8
160
200

0.8
160
200

1.2
240
200

0.8
100
125

0.8
160
200

1.2
240
200

1.2
150
125

0.8
160
200

0.8
100
125

1.2
150
125

1.2
240
200

1.2
150
125

1.2
150
125

0.8
100
125

0.8
100
125

1.2
240
200
The R squared for AB in this case is about 0.96 which leads to a high VIF.    So, you have to stay with the coded levels?
Second question: if you just do the classical two level designs (full or fractional), do you really need to even check the VIF?  Won’t it always be 1?
Thanks a lot.

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#157575

lin
Participant

Thanks for the reply Robert.  Then I don’t understand how VIF is calculated.  From an earlier post of yours (I did try to find the answer), you said:
“When you are looking at the R2 in the VIF you are looking at the relationship between the X’s. In the VIF case R2 is the square of the multiple correlation coefficient from the regression of the ith X on all of the other X’s in the equation.  An R2 of 1, in this case, would indicate a perfect linear relationship between two X’s (perfect confounding).”
Supose I have two factors, A and B.  They are independent.  But AB is the product of the two.  Is it not impossible for VIF for AB to be 1 when it is determined by the product of A and B.  Is not the VIF for AB the R2 value obtained by treating AB as if it was Y and regressing with A and B?
Than ks

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#157094

lin
Participant

Lots of replies already.  I don’t see the most obvious thing I would do.  If you have a high Cpk and your process is really in statistical control – consistent and predictable – reduce your frequency of sampling.  Whether you use a control chart to continue monitoring is your choice.  I would.  It was important to chart at one time.  I would keep it going, just sample less frequency.  I believe it always best to look at data as a time series chart – with limits wherever possible.  It is the way process communicates with you.  The correct interpretation will tell  you if something has changed or if everything remains the same.

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#155997

lin
Participant

If you analyze the data without lag, there are a number of out of control situations.  Point 8 (223.2) is just below the LCL (also out on the range chart).  The last 8 points in a row are above the average with the last one being above the UCL.  It appears something has caused the average to move up for those last 8 points – a special cause of variation.

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#155942

lin
Participant

PV,
ISSSP is launching an MBB assessment model.  I’m not sure what credibility it will have in the market, but at least it does not force you to pay for training to develop skills that you have already mastered.
Good luck.

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#155734

lin
Participant

Hello Vaughn,
I stand corrected.  You are for real.  There is one approach you might consider.  You want to create systems to manage your growth.  You can also look at that in terms of creating or improving processes for growth.  While every company is unique, there are many processes that most organizations perform.  The American Producitivty and Quality Center (http://www.apqc.org) has developed the Process Classificaiton Framerwork to aide in benchmarking of organizations.  This framework actually provides a great method for process management and determining what your company needs.
There are twelve primary processes.  Five of these are operating processes.  The rest are management and support processes.  The primary processes are:

Developing Vision and Strategy

Designing and Developing Products and Service

Marketing and Selling Products and Services

Delivering Products and Services

Managing Customer Service

Developing and Managing Human Capital

Managing Information Technology

Managing Financial Resources

Acquiring, Constructing, and Managing Property

Managing Environmental Health and Safety

Managing External Relationships

Managing Knowledge, Improvement, and Change
If you download the Process Classification Framework from their website, it will give the secondary and work processes under each of these.
http://www.apqc.org/portal/apqc/ksn?paf_gear_id=contentgearhome&paf_dm=full&pageselect=detail&docid=121388
The place to start, if you haven’t already, is with the vision and strategy piece.
With each primary process, I would use a five step model to ensure the process is developed as best it can be for your company and growth.  The model is Define, Document, Measure, Manage and Improve.  This five-step model helps you implement process management.  But enough on this for now.  I think you might find the process classification framework interesting.
Bill

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#155573

lin
Participant

Hello Vaughn,
Bill

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#155375

lin
Participant

If you believe what Bisk Education (University Alliance) is telling you about the ASQ pass rate, then you are really naive.  Bisk has no access to ASQ pass rate data.

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#155250

lin
Participant

First off, zero outages is an unrealistic goal.  It is not going to happen.  I would track it based on time: time down/total time per week and use a X-mR chart.  The number of outages really doesn’t tell you anything.   I would want to know the % of time the system is not available.

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#154891

lin
Participant

Where are you located and in what industry?

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#154862

lin
Participant

Thanks for answering.  I have gone beyond the comic books. I have read Box, Hunter and Hunter in detail.  I have Montgomery’s book.  All I wanted from my questions was some answers from people who have done quite a few experimental designs.

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#154156

lin
Participant

I am glad you fellows came up with the simple definition of “opportunity”.
Now I am really confused?
For us (I may be the only one reading that is not a
Six Sigma engineer)just starting out, I take what I am reading as opportunity is an event in which either conformance or non-conformance can be added to the realization of a product. The more opportunities it takes to reach conformance to customer satisfaction, the more waste. The goal is the fewest possible.
Now you can go back and talk “baselining”.

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#152962

lin
Participant

Sorry, not a stats guy here (don’t really deal in minitab speak), but if your customer told you they think your spec is too wide and you have observed out of control measurements that are within some spec that was set by engineering 4 years ago, your spec is probably wrong and you need to go back to the DM part of the process to determine proper VOC.  Call me crazy, but if you work for a company that considers profits important (most do), your company really should value your customer’s input with regard to their requirements.
That being said, if you observe an out of control measurement that is over the favorable line of an upper or lower spec limit, you would be foolish not to try to determine the cause of that particular variation.
FYI, I’m not GB, BB or any other B.  I just find this forum strangely interesting and informative….sometimes.  So take what I say with a large grain of salt.

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#152629

lin
Participant

Thanks KKN
There is a reason I requested a simple explanation.
I am a “grasshopper” to the Quality paradigm. I read the explanations and it intimidates me because I do not have your back ground. The experts need to consider that “grass hoppers” are lurking trying to improve.
For years I rode a motorcycle, a Yamaha. All this time Harley owners disdained foreign bike owners. They also were upset with car drivers that did not “see” them and thus there were injuries to the bike riders. Now, if car owners also rode motorcycles, any motorcycle, they would be more respectful of bike riders. Harley riders knowing that HD could never manufacture all the bikes needed to service the entire market should have been happy to see anyone riding a motorcycle because it made their life safer. The more riders the better.
The trained Six Sigma belts should consider that little “grass hoppers” are looking for tidbits of understanding and if we learn something the entire Quality paradigm strengthens thus supporting your
efforts. Maybe the real jargon explanation with an interpretation for “junior”.
I love the Quality Management concept but I am not an engineer.

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#152597

lin
Participant

Please fellows, explain this in an easy to understand
non-engineer way.
What is the difference?

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#150937

lin
Participant

A good Gage R&R study will use control charts to check for bias and consistency between and within the operators.  I assume this is what you mean by out of control.
For example,  suppose you have done a gage R&R with the three operators, ten parts and three trials.  You can and should do a range chart on each operator.  You take operator’s A results and plot them on the range chart, determine Rbar and the UCLr for a subgroup size of 3.  If this chart is out of control, it means that the range of results opeartor A gets is not consistent from part to part.  You should investigate why this occurs.  Since the results are not in control, you don’t know what would happen if you run the Gage R&R again.  So, find out why the operator is out of control.  You can take the same approach for checking the bias and consistency between operators.

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#150846

lin
Participant

Yet another student of Harry’s Handbook of Stupid Superlatives.
Leave out the SS BS and try some facts Shoddy Roddy boy

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#150800

lin
Participant

If you have Excel 2003, there is a Weibull function built-in.

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#150705

lin
Participant

Hello Dave,
As stated by the previous poster, p charts do have subgroups.  For example, suppose you are monitoring the fraction of invoices that are priced correctly each day.  You randomly select 100 invoices a day.  This is your subgroup and n is the subgroup size – in this case 100.  Suppose 98 of these are priced correctly.  This is np.  You can then calculate p for this subgroup as follows:
p = np/n = 98/100 = 0.98
So, there are subgroups with p charts.
Best of luck to you.

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#150702

lin
Participant

It may be that your subgroup size is too large.  This makes the control limits very tight and generate out of control points.  You can move to weekly data and keep the p control chart.  There is also a good possibility that, if you are monitoring more than one defect, that the conditions for using the p control chart are not met.
Consider using an individuals control chart for the %.

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#150618

lin
Participant

I  think the original book by Chambers and Wheeler, Understanding Statistical Process Control, is one of the best.  Wheeler has some very good books on SPC at http://www.spcpress.com.  But as suggested before, start with Dr. Deming.  Out of the Crisis is good as suggested.  Not an easy read.  But understanding Dr. Deming’s system of profound knowledge is very important for continuous improvement.  SPC is affected by all four bodies.

0
#148755

lin
Participant

The professor is generally wrong.  Use the sigma table using DPMO, but recognize the corresponding “sigma” is just an estimate of the short term capability.  If your DPMO is about 6,800 (long-term capability) then your estimate of short-term capability will likely be about 4 sigma.  When using defect data, you can compute your long-term capability fairly well, but without switching to continunuous data, you can not estimate short-term capability.  In this case you just add “1.5 sigma” to create an approximation of the short-term capability.  If you have access to continuous data, then use it and compute the actual short-term capability.  The 1.5 sigma shift is just a best-guess model you can use if no other information is available.  The 1.5 shift is just a way to remove assignable causes from the long-term defect data so you can “guess” what the short-term capability could be.

0
#148255

lin
Participant

Well said Mike.  We might also wonder, since there have been far more than 58 large companies that have deployed Six Sigma, how the sample of 58 was selected.

0
#148194

lin
Participant

Here at Kodak, “end to end” refers to the value chain from research all the way to manufacturing and post-sale support.  It also refers to the imaging flow of capture->storage->manipulation->printing and sharing.  The latter applies equally well to the old film products and the current digital products.

0
#147090

lin
Participant

DK
Do you know why Dr. Harry parted ways with ASU for six sigma training?

0
#146896

lin
Participant

A touch of sanity. As Philip says normality can never be tested in practise beyond +/-3 sigma. Even at this level, 3,200 data points are needed !
However, there is no need for tests of normality in quality improvement.  Use Shewhart Charts – Normality is not required.

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#146810

lin
Participant

ASQ Certification may be recognized, but so is the Yugo, so recognition does not equal quality.  Maybe in the land of the blind, the one-eyed man is king, but in my opinion the ASQ process suffers from several serious weaknesses:
1) The project requirement is easily “gamed”.  Nobody reviews the actual project, only an affidavit, which can be signed by anyone at your sponsoring organization, and there is no assessment of that person’s qualifications to determine the quality of a project.  Many people “re-purpose” old projects that were not even DMAIC projects, like IT upgrades, for the purpose of satisfying the project requirement in order to sit for the exam.
2) If you accept that the purpose of a Six Sigma exam should be to validate that the person being examined can perform Six Sigma work effectively in the real world, then the ASQ exam has several severe limitations:  no graphical interpretation, no large datasets, and a reliance on hand calculations.  Who, in this day and age, uses paper-based statistical tables to look up values? People don’t do the work that way, so why structure and exam that doesn’t reflect the way people do the work?  People in the real world use statistical software, so the exam should include a component that tests the ability to run and interpret analysis from a statistical software package.  And this doesn’t even touch on the assessment of soft skills, which are probably much more important in the final analysis.
So, ASQ certification may be nice to have, and in the absence of anything else, it might represent minimum evidence of competence…but it doesn’t carry any weight with me when I hire people unless there is much more to the story and a lot of solid experience.
Just my opinion.

0
#146797

lin
Participant

Try looking at the iSixSigma directory here: https://www.isixsigma.com/co/six_sigma_online_training/six_sigma_online_training.asp
Note that there is no quality assessment of the listed products.
Or search the discussion forum for previous posts.  You’ll find a lot of comments.

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#145721

lin
Participant

Yes, you can add upper and lower control limits to efficiencies and yields.  I would use the X-mR chart.
Bill

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#145510

lin
Participant

Bechtel has been using Six Sigma for a number of years on it’s EPC activities. I my self while at Bechtel attempted to improve ES&H preformance using Lean Six Sigma methodologies. Do you have a specific problem or question?
Bill

0
#145287

lin
Participant

You are not missing anything.  There is no direct correlation between the two.  Cpk is calculated using the estimated standard deviation from a range chart.  Ppk is calculated using the standard deviation calculated from all the data.  There is no correlation between those two standard devaitions, although they should be close to one another if the process is in control.  The more out of control the process is, the more difference there will be.

Bill

0
#145263

lin
Participant

Please post your data.  Your approach seems OK, but something is not right that 32 of 35 data points are out of control.

0
#145142

lin
Participant

Sorry there SS Shooter … I didn’t realise that you were one of the crowd who had woken up to how much rubbish is in SS  !!!
Harry and Reigle probably don’t care much now … I can imagine they spend their days laughing at the foolishness and gullibility of the masses, while counting their millions …

0
#145140

lin
Participant

Bravo !!  Economic limits.
Perhaps you can explain it to the other SS ignoramuses here … if they understood the basics, there would be no 1.5 sigma shift, no 3.4 DPMO, no hypothesis tests and all the other SS rubbish.

0
#145125

lin
Participant

Andy,
If Shewart is a genius as you say, why don’t all these SS idiots read his work ?
When will people realise that control limits are not probability limits ?

0
#144716

lin
Participant

wea3497@aol.com
Thanks!
Bill

0
#144560

lin
Participant

Flavious,
Please re-read Darth’s reply and you will get your answer.  But I will repeat it.   The distribution of range samples DO NOT follow a normal distribution.  The zones test should not be applied to the range chart.  And please do follow his advise and read Dr. Wheeler.  He will explain why it is not the central limit theorem that makes the Xbar chart work.
Bill

0
#144551

lin
Participant

I agree with you.  I still need to answer their question and I don’t think that the math given before works out.

0
#143754

lin
Participant

Of course, Darth is correct in his analysis since this is a homework problem.  But it is too bad that they don’t teach that an average has no meaning without knowing the state of the process that generated it.  Is the process in control or there are special causes present?  For example, the data below generates an average of 6.2.  Taking the standard deviation to be the square root of 6.2 would give misleading information.  Always check the state of control.

3

0

0

0

0

3

2

3

4

1

2

3

0

0

130

0

0

2

0

0

0

2

0

0

0

0
#142770

lin
Participant

Same identical question asked by Maureen on Aug 24.  ??

0
#142280

lin
Participant

Three sigma limits are appropriate at all times.  But don’t confuse the issue of statistical control with capability.  You want to control the process but also have it capable of meeting whatever spec you have for the active ingredient.  You probably want a very capable process there, at least Cpk = 2.

0
#142072

lin
Participant

The type of chart you are using is an individuals control chart.  The control limits for this type of chart are:
UCLx = Xbar + 2.66Rbar
LCLx = Xbar – 2.66Rbar
UCLr = 3.27Rbar
LCLr = None
Rbar is the average range from the moving range chart.  The range is the difference between consecutive data points.  For example, the range between the first and second data points is 0.09.
Rbar for your data is 0.551, so
UCLx = 3.742 +  2.66(0.551) = 5.208
The estimate standard deviation from the range chart is Rbar/1.128 = 0.49.  This is much less than the calculated standard deviation of 0.83.  This is an indication that the process is out of control, which it definitely is by looking at the X chart.
On the comment that you can’t go further because the range chart is out of control.  Not true.  What it does mean is that the you may not have a good Rbar, but you have only one point out of control on the range chart.  Not a big deal with 56 points.  Regardless, all it does is inflate Rbar which means that the points beyond the limit on the X chart are still out of control.  Also, the runs you have above and below average as well as the trends on the X chart still apply.

0
#142062

lin
Participant

Are you sure the data you posted was correct.   I get a different average (3.66).  No sense going any further.

0
#142048

lin
Participant

That is not true about Excel  The STDEV function of excel calculates the standard deviation using n-1 regardless of the size of the sample.
If you want the population standard deviation, you use STDEVP.
Excel does not give you the wrong answer when you have more than 30 data points when you are using STDEV.  Simply not true.

0
#141912

lin
Participant

I used X-mR chart to monitor sales quite often.  For a chart that is trending up, you can use the best fit line for the average line on the X chart (x = bo + b1t where t is the week number).  Then the control limits become:
UCLx = bo + b1t + 2.66Rbar
LCLx = bo+b1t – 2.66Rbar
where Rbar is the average range on the moving range chart of 2.  No different that then normal moving range chart.
Start with five weeks of data; recalculate limits each week with new regression line until you get about 20 weeks of data.  Then you can probably use those limits into the future.
The problem I have seen with using weekly data for established products is that the last week of the month is almost always the largest.

Bill

0
#141533

lin
Participant

Here is a link that explains the transformation.
http://www.itl.nist.gov/div898/handbook/pmc/section5/pmc52.htm

0
#141532

lin
Participant

The Box-Cox power transformation is given by (L = lambda):
x(L)=(x^L-1)/L for L0
x(L)=ln(x) for L = 0
Then you find the value of L by maximizing the logarithm of the likelihood function (which I won’t give here).
I just wondered if there were any bounds on lambda.  I don’t think so.
Thanks,
Bill

0
#141445

lin
Participant

TQM was not “all about defect reduction.”
As Dr. Deming said, “Improve constantly and forever.  Constantly strive to reduce variation.”

Bill

0
#141195

lin
Participant

From what I can see from previous posts there has been no critique of Dr Burns paper.  All I can find is childish personal attacks and gutter sniping.  Personal attacks are not appropriate with the large number of authors at the http://users.bigpond.net.au/SixSigmaFallacies/  site.  Let’s see some constructive discussion of the CONTENT of these papers.
These papers do present clear and superior alternatives to six sigma. Dr Wheeler in particular spells this out clearly in his books.  Perhaps you feel that Dr Wheeler is flawed ?

0
#141194

lin
Participant

How was Dr Burns “torn up” as you suggest ?  What are the specific errors in his paper … it sounded very convincing to me.

0
#141166

lin
Participant

Any one of us could die any minute … heart attack, traffic accident, whatever.  I’ve had 30,485,666 such opportunities for death … which puts me well in excess of six sigma.
It makes about as much sense as attaching a sigma level to any process. For some reality, read the articles here :
http://users.bigpond.net.au/SixSigmaFallacies/

0
#140925

lin
Participant

It is NOT “okay” to use the calculated standard deviation for the individuals chart.  This greatly inflates the control limits for processes that are not in control.  Use the moving range of two.

0
#140511

lin
Participant

Thanks for all your effort Robert.  Your results confirm what I got.  I am not clear on what you mean  about not centering and scaling the X variables.  The coding (using the equation you gave as I did) does that, doesn’t it?

0
#140464

lin
Participant

Hello Deep,
Yes, I multiplied A and B.  Also, I ran the regression on the coded factors and got the same results as for the DOE ANOVA.  Below is the data:

Standard Run Number
A
B
Result 1
Result 2
Result 3

1

74
78
73

2
+

65
64
69

3

+
74
76
78

4
+
+
85
88
91
A is temperature with range from 30 to 90
B is residence time with range from 15 to 45
Thanks.

0
#140212

lin
Participant

The sample means will be normal as long as your subgroup size is large enough.  Subgroup sizes of 4 to 5 are usually enough but for data that is extremely skewed.

0
#140095

lin
Participant

I am not sure of your process.  But your Cpk is less than 1.  Without 100% inspection, you will send pieces out that are not in spec.

0
#140069

lin
Participant

Matt,
Great!!! Email me please at bstorey100200@yahoo.com
Thanks,
Bill

0
#139958

lin
Participant

Two others to look at: SPC for MS Excel and SPC IV Excel.

0
#139957

lin
Participant

There are a number of things you can do.  If you want an accuracy of +/- 5 %, you will need to send out the survey to about 357 people.  That is too many to call, but you could send out the survey via e-mail and follow-up with those who do not respond.  If leadership does it role in making sure people know this important to respond to, you hopefully won’t have too many to follow up with.

0
#139955

lin
Participant

There are a number of Excel based SPC programs out there that make it easy to do control charts and other stats in an Excel environment.  Just search “spc excel” to see what is available.

0
#139252

lin
Participant

Below is a link for teaching some of the basic SPC tools using colored candies (like peanut M&M’s).  The info is in the Annex A7.7

http://www.ca.com/de/blast/k7/hdi_chapter_7.pdf

0
#139203

lin
Participant

This link has a good three part series on Cpk and Ppk.
http://www.spcforexcel.com/articleslist.htm

0
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