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Missing term in multivariate logistic likelihood? #24
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Which document are you looking at? i.e. which doc is where "Tech doc equation 11" is from? Can you put a link here.. |
It's in iSCAMTechDoc.pdf |
OK, where are you getting this equation from: |
That's equation L.9 in Table 3 of Richards and Schnute (1995), after taking the log |
I'm having a hard time getting what you have from Eq 9, I get this after logging it:
So |
I have Both |
The ADMB source code is completely undocumented and convoluted, and every time I look at it I feel a little sick. I think it could be this: |
I think that's the link to the multinomial likelihood. I see the Looks like dmvlogistic is also distributed in ADMB: |
I was working through the derivation of Tech Doc equation 11, which seems to be missing a 0.5 term.
If the log-likelihood is
-(A-1) * T * log(tau) - 0.5 * sum(eta^2)/tau^2
, then substitution of the equation just above no. 11 should result in-0.5 * (A - 1) * T * log(tau^2) + constant
sincelog(tau) = 0.5 * log(tau^2)
. Schnute and Richards (1995) also seem to be missing this 0.5 term in Table 4, L14, but the derivation is analogous to Appendix D of the ADMB manual which does have this 0.5 term.Does the ADMB code have the 0.5 in the likelihood?
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