Chip Hewette

I was just seeking to clarify the original question with my statement that a value for sigma is not on the X-Bar / Range chart.  It is not calculated from a single subgroup on this type of chart.  I am aware of the two graphs on X-Bar and Range charts.

Could you clarify what you mean by “shift in sigma?”  I’m unaware of a sigma value on the X-Bar/Range Chart.
If you are asking “how do I determine if what I did made a difference?” you may need to use another tool.  Charts are often slow to respond to experimentation.
If you have a long run chart showing X-bar and R-bar, from which you gather t…[Read more]

An unstable process can still operate within customer specifications.  Does yours?  It sounds like you are worried that some parts will not be in specification.
100% inspection is not always effective.  Sampling is not appropriate to find random errors.  Think of the statistics.  If we measure every tenth part, we have a 1 in 10 chance of find…[Read more]

I hope you can succeed!
Have you followed DMAIC in this project?  Poka-yokes are great, but have you identified the issues at hand?  Pardon me if you’ve already considered the following…
Missing dimensions are often found when the drawing reaches the fabrication shop.  Who are other customers of the drawing?  What do they complain abo…[Read more]

Are you speaking of validation of a device or medicine to be equivalent to a currently used device or medicine?
For example, let’s say a currently used device can detect 10 cases of cancer when there are truly 12 cases of cancer.  Based on this poor performance someone makes a new device to find the 12 true cases of cancer.  Are you looking for…[Read more]

In the DMAIC flow of events, it may be necessary to present the Gage R&R as something of great importance to the internal or external customer.  To present the results, try to simplify by showing (1)the item being measured, (2)the specified dimensions, and (3)the proportion of the width of the specifications absorbed by the variation of the…[Read more]

Control charts don’t have to have a single X double bar value.  Control can be monitored as the average moves continuously lower and lower.  The key is to understand the “expected” shift downwards, and alert the operator when the individual value or subgroup average exceeds the control limits based on the expected trend downward.
Understanding t…[Read more]

I suggest that a practical review of the engine crankshaft tolerances be performed first.  It is not always possible to have an operating engine with all combinations of part tolerances.  Putting component tolerances in any orthogonal array can be a disaster, in that the engine would self-destruct if certain part dimensions combine.
It makes m…[Read more]

Home Depot is a prime example of a full commitment to Six Sigma in retailing.  There are other companies considering Six Sigma. 

Although I’ve never read the cited work, I have read Dr. Wheeler’s book Understanding Variation, and sat in a private seminar given by Dr. Wheeler at my employer.  Is this like staying at a Holiday Inn Express?
Perhaps the meaning is simply that converting from Cpk to dpmo for the population is inaccurate unless the underlying distribution of…[Read more]

You might contact Dr. Robert Mees at the University of Tennessee, Knoxville to inquire about master’s theses in continuous improvement.

Maybe…Develop through background research the set of events / treatments to treat ‘defect.’Study the variety in treatments (some doctors use one medicine, some use another, etc.)Establish using normal quality chart methods (Pareto, histogram)  the ‘normal’ response to the defect.  Obtain buy-in from champion and process owner that this is the ‘…[Read more]

If you have a sponsor who would appreciate a structured improvement project within his span of control, ask that person.  A green belt or black belt can uncover potential projects, but should not be the project owner.  He should be the project leader, of course, but not the owner.  What questions does the sponsor face to which there are no ap…[Read more]

There is an absolute maximum length of time your company desires to spend on a design project.  As you stated, there is no lower limit, aside from the practical space-time continuum boundary.  Some internal customer, perhaps the VP of  Engineering, could set the desired maximum length of time.
Granted, each project may fit into various types, ra…[Read more]

Cpk is often used to give people a sense of ‘goodness’ about a production process.  Calculating Cpk based on a single sample from a process is, in my view, an incorrect use of the Cpk calculation.  If one is lucky, and all the parts are similar, the Cpk looks good.  Later, when the process drifts, the customer calls and says “Why are you se…[Read more]

Bank of America has 6S.

In a meeting, I once tossed a coin eight times and got heads every time.  Did not succeed in demonstrating randomness!

I think we can help, but we need more info.
1.  What are you measuring within the 1264 accounts?
2.  What do you want to know about that measurement?  The average value for the measurement from a sample within 1264 accounts?
3.  Do you want to detect a 5 percentage point shift from an average historical value to a ‘new’ value?

As usual, it depends.  Diesel efficiency and emissions are affected by the fuel injection system.  Direct and indirect injection systems exist.
Diesels are ignited by extraordinary compression of a ‘perfect’ gas, the temperature of which is raised to the point where atomized fuel ignites.

There is an old Andy Griffith episode where a new deputy takes all the past data and predicts that a certain law would be broken near midnight on a certain date.  The episode pokes fun at science and statistics, with good reason.  It is very difficult to make predictions!
I assume your past data contains information that some would consider ‘p…[Read more]