On Mon, May 05, 2014 at 10:24:07PM +0200, John Darrington wrote: > On Mon, May 05, 2014 at 11:27:40AM -0700, Ben Pfaff wrote: > On Mon, May 5, 2014 at 10:51 AM, John Darrington > <[email protected]> wrote: > > On Mon, May 05, 2014 at 08:09:16AM -0700, Ben Pfaff wrote: > > I'm sure there is an error in our implementation. NaN is coming > from > > the square root of a negative number, as you said. > > > > I made another mistake below. PSPP actually calculates ASE0 > correctly > > for asymmetric lambda (lambda divided by ASE0 is what's displayed > as > > "Approx. T", which matches that calculated by SPSS for asymmetric > > lambda). It's ASE1, displayed as "Asymp. Std. Error", that PSPP > gets > > wrong. > > > > Ahh. I was calculating ASE0. > > > > ASE1 like you say seems wierd and results in an imaginary number. I > can only imagine > > that this is a mistake in the SPSS documentation. Unfortunately I > haven't been able > > to find any other references on how to calculate this value. > > > > Another issue: if we have T, we should be able to calculate the > significance. We just > > need to know the degrees of freedom. I wonder how these are > calculated? > > > > Unfortunately the litereature on these values seems to be scarce. > > https://v8doc.sas.com/sashtml/stat/chap28/sect20.htm has a different > formula, > but I don't understand how to interpret r_i|l_i = l. > > The text below it says: > Also, let li be the unique value of j such that ri=nij, and let l be the > unique value of j such that r = n??j. > > I interpret this to mean that r_i is summed for all i where the condition l_i > == l is true.
I can't seem to get anything sensible out of that formula either. For now, I removed the calculation entirely, so that PSPP displays nothing instead of a wrong answer.
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