topic Re: JMP offers specification proposal? in Discussions

JMP offers specification proposal?

MikeKim — Wed, 20 Sep 2023 08:55:00 GMT

Hi.

Supposing that I have bunch of data but no Specification (LSL and USL).

Data are diagnosed as to follow SHASH or other non-normal distribution.

Is there appropriate analougues for the plus/minus 3 SD for normal distribution? (Since 6SD of normal distribution is usually used as Specification Tolerance)

Alternatively, is there function that JMP calculated the possible Specification which ensures specific % will be preserved within the Tolerance? (for the SHASH or Weibull or other distributed data)

Thank you!

Re: JMP offers specification proposal?

jthi — Wed, 20 Sep 2023 09:07:24 GMT

I won't go to the discussion what should determine your specification limits (there are already good topics regarding this in community) or how they should be calculated, but below are some examples what JMP can do

Re: JMP offers specification proposal?

SamGardner — Thu, 21 Sep 2023 14:26:51 GMT

Look into Tolerance Intervals. There is a non-parametric option you can use. Available in Distribution.

Re: JMP offers specification proposal?

SamGardner — Thu, 21 Sep 2023 14:30:45 GMT

Also, you can fit the SHASH distribution to the data, then save the transformed values to the data table, that transform the data to look like a normal distribution. You could then calculate tolerance limits on that transformed data and do the backwards transformation to the original scale of the data.

Re: JMP offers specification proposal?

SamGardner — Thu, 21 Sep 2023 14:34:47 GMT

There is a SHASHInv( ) function you can use in a table column or a JMP script to do the back transformation.