Hi,
This is something I forgot to ask during the past Montpellier workshop, so here I am (again!).
I am dealing now with an analysis where individuals were sexed since the 3rd occasion (total=14 occasions).
These are the states:
1=female
2=male
3=dead
and these are the events:
0=not seen
1=captured and identified as male
2=captured and identified as female
3=captured and sex unidentified
The INITIAL STATE pattern matrix would be:
p*
and the Event step two (SEX IDENTIFICATION) would be:
*---
-p-*
--p*
As the INITIAL STATE is not estimable for the two first parameters (there are not sexed individuals), I would use the sentence "t(3_14)" and for the SEX IDENTIFICATION I would use f.t(3_14).
I have tried to use as alternative GEMACO sentence in SEX IDENTIFCATION "f.t(3_14)+t(1 2)" (instead of "f.t(3_14)" alone) and set the second part (t(1 2))=0 in the IVFV. I get different results in terms of deviance and AIC (the ranking is not affected). This is a bit confounding to me because in these cases if you don't specify nothing about these somehow nonsensical parameters (in this case the first two occasions) in GEMACO, ESURGE will try to estimate these parameters because they are not structurally unestimable (I mean it is not as the case of age2 in t1 for instance). In some way there are not "good" data to do that, i.e. in this case there are not sexed individuals but yes there are captures.
Question:
So, in general terms what is the correct way to deal with this? writing down a sentence like "f.t(3_14)" or using a sentence like "f.t(3_14)+t(1 2)" and setting the second part equal to zero in the IVFV?
Hope you are doing well,
Thanks
Simone