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Johnson su distribution

JMP reports the following parameters with respect to a fitted Johnson su distribution 1) shape (lambda), 2) shape (delta), 3) Location (BETA), and 4) Scale (sigma).

I would like to use the Johnson su distribution in the discrete element simulation program EXTEND6. EXTEND6 does accommodate the Johnson su but requires the following parametric inputs 1) Lambda, 2) Gamma, 3) delta, and 4) Location.

I am concerned about putting the right paramaters from JMP into the correct fields in EXTEND6.

Can anyone out there provide some insight. I have searched the software manuals for each program and have come up empty.

Thank you!

Re: Johnson su distribution

The JMP 8 documentation now includes the pdf's for all the distributions. The pdf's for all the Johnson distributions are given. Without knowing the parameterization or form of the pdf used in EXTEND6, I'm unable to say what parameters in JMP match up to what parameters in EXTEND6.

You can download (for free) the JMP 8 documentation at You want the Statistics and Graphics Guide. Go to chapter 4, and look in the distribution fitting section, and look for the Johnson distributions.

Also of help in understanding the parameters may be the jsl function indexes available in JMP. Choose Help>Indexes>JSL Functions. Then look for the Johnson Su Density function. Click the Run Example button. A plot is generated with sliders for the parameters. Playing with the sliders may help you understand how the parameters influence the distribution.

Re: Johnson su distribution

Thank you for your reply. It appears that "Help>Indexes>JSL Functions" is not available in JMP 7.0.2 - is that correct?



Jun 23, 2011

Re: Johnson su distribution

I think it's called "JSL Operators" in JMP 7, but it's the same thing.