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JMP 12 Process Capability Calculations

alan_ruttle

Community Trekker

Joined:

Jun 23, 2014

Hi all,

I have a couple of questions on how JMP 12 handles process capability calculations:

  1. How does JMP handles calculations when a subgroup ID column is not referenced?
  2. What formula does JMP use for the Std dev for the within Sigma Capability Summary Report?
3 REPLIES
Peter_Bartell

Joined:

Jun 5, 2014

The statistical details section of the Process Capability platform can be found here:

Statistical Details for the Process Capability Platform

alan_ruttle

Community Trekker

Joined:

Jun 23, 2014

Thanks Peter, this is exactly what I was looking for.

Peter_Bartell

Joined:

Jun 5, 2014

Alan:

Your welcome.

Back when I worked in industry, and I was asked to cite process capability indices, I ALWAYS included some sort of graphical image too that communicates so much more about process capability over just a simple statistic like a Cpk or Ppk. Cpk's and their ilk can't show you anything about location or shape of the distribution. Can't show you unusual or interesting observations. Frankly I feel that people that blindly use just process capability indices without graphical supplements, are falling victim to a dreaded disease I call "Mononumerosis". This disease can be deadly in quality and statistics...trying to distill lots of information into one single number.

Luckily, there are several data visualization options available within the JMP version 12 Process Capability platform report architecture which help avoid Mononumerosis. The Goal Plot (useful for multiple critical to function/quality characteristics), the Standardized Box Plots, and the good old fashioned histograms (still my favorite for a single characteristic) within the Individual Detail Reports are some to consider.