Saherngu

All your responses, answered my question.
This is the story:
We were evaluating Cpk and Ppk index from a CNC machine and we were trying to understand how measurement equipment affects these index. Also, MSA manual on page 116 has a note regarding process variation and tolerance.
Sus respuestas contestaron mi pregunta.
Ésta es la h…[Read more]

Thanks for your response.
The fact is this: I can analyse %GRR from two ways: 1) Based on the tolerance range, and 2) Based on process variation. My question is: Wich way (1 or 2) have I to use and why? Thankns again. 
Gracias por su respuesta.
El caso es: Yo puedo analizar el %GRR de dos formas: 1) Basado en la tolenacia total, y 2) Basado e…[Read more]

I’m in the direct marketing business and went through six sigma training heavily skewed towards engineers.  Even though most discussion problems has an engineerign bent, I sitll found the course to be very useful and applicable to my industry.
From my perspective, the six sigma template is the same regardless of the industry.  So, I wouldn’t sp…[Read more]

Does anyone know how Strip Plot experiments are handled differently from Split Plot experiments?

Thanks Bjorn. 
I’m somewhat familiar with split plots, but not strip plots.  Of what I know, there would be a whole plot for each of my 2 factors (Voltage and Elecrical Pulses).
Do you know of sources for more information (preferably with a few examples carried out)?  It’s always nice to see an example – especially done with a software (Minitab for me).

Stan,
Your question relates to the difference between defective and defects.  Within each process, each opportunity to create an error is a defect.  If your process has 8 distinct opportunities to create an error, then any error within that process would be a defect.  If making that defect renders the part unusable, then the part would be de…[Read more]

Robert,
Thank you for the DOE advice and the references.  Much appreciated.

Robert – please ignore the 1st line in the last post.  I checked the posting and noticed the 1st line, which shouldn’t be there.
Just to clarify:  the 3 solids will, by volume, occupy either 7.5% of the overall volume or 30.0% of the overall volume.  The remainder is occupied by liquid.
James

The 4th factor is the amount that the mixture takes up in the overall volume (either 7.5% or 30.0%).
Robert,
I’ll try to clear up my description.  My initial description was per the 1st way I thought of creating the test matrix (with a mixture of 3 items – sand, rock, and metal; and then adding another factor for the % volume that this 3…[Read more]

Mike,
All good points.  I’m calling them “process factors”, but they’re really environmental conditions if anything – noise in the real world, but chosen to be controlled for this experiment.  “Process factors” is Minitab language.
Particle size and density should can be independent, if chosen to be.  I need to verify if the levels chosen for pa…[Read more]

Thank you, Robert.
Sorry if my previous post was not clear.  The mixture is made of 3 solids (sand, metal, rock) and a liquid solution.  As Mike had suggested, maybe the best way to create the test matrix is with a mixture of 4 factors (sand, metal, rock, and liquid solution) – with the %’s defined by volume.  Which do you think is best?
If th…[Read more]

Mike,
Thanks for the response.  I think that you make a good point.  The 3 materials (actually sand, metal, and rock) are combined in a mix at different proportions.  For each run, this mix is put into a liquid solution.  The liquid solution really should be the 4th part of the overall mix.  So, it does sound like a 4 factor mixture DOE.  The 4…[Read more]

Would appreciate any response to the previous note.  Thank you.

I don’t agree with the NEVER – the key is the basis of the underlying data
For example – what about a concentration where the result is expressed as a percentage………
Concentration = weight of ABCD / total weight
weight is a continuous variable therefore the % is a continuous variable in this case
 

7 point Likert Scale is my preference. Generally speaking, the 7 point scale provides more granularity and hence better decision making. Though, I would provide a description of the scale, such asStrongly Neither Strongly
disagree Agree or Disagree Agree
1…………….4…………….7

Hi Maer,
That’s a very good question.To understand the significance of the “true innovation” that was key to the development of six sigma, you need to mentally transport yourself to the late 1980’s. What was going on at that time with respect to Quality? Who were the Gurus and what was their message.Most of them were using Statistical Pro…[Read more]

Gary, Thanks a lot for your help.
James

(Zsq * p(1-P)/margin of error))sq
Ex.  (95% confidence level and a 5% margin of error yields a sample size of 368.
 
(1.96sq*.50(1-.50)/.05))sq=368
The .50 is used assuming you don’t have an idea what the desired response rate might be.  If you do, say 25%, then P(1-P) is .25(1-.25) or .1875
 
Find the 1.96 in the Z table.  Some tabl…[Read more]

Consistency around the mean, not within upper and lower limits (cp)

Stated simply, the confidence level, say 95%, is how confident you are that you would find a mean very similar to the mean in a current sample if the test were repeated in a similar fashion.  Confidence interval, say 5%, is indicative of the true value (mean) or range of your mean from a sample study.  Example, the mean is 37%.  In this case wi…[Read more]