dear all,
I would like to ask your help on the following model:
I have data for the size of zooplankon in lakes with (Y) and without
(N) introduced fish. there are 15 size classes with 1 the smallest
and 15 the largest. Number of zooplankton samples in each class are
as follows (cumulated over all lakes):
N Y
1 7901 24174
2 2869 2331
3 964 737
4 1573 621
5 1857 584
6 2073 777
7 2078 548
8 919 171
9 485 28
10 239 3
11 64 0
13 30 0
14 3 0
15 1 0
To test the hypothesis that fish eat the biggest zooplanktons,
as I have repeated measures in different lakes, I thought to model
this data as follows,:
prior=list(R=list(V=1, fix=1), G=list(G1=list(V=1, nu=0)))
mod1<-MCMCglmm(CLASS~Fish-1,
random=~lago,family="ordinal",data=dimensioni.dat, prior=prior)
where CLASS is the size class and "Fish" the variable indicating if
the lake has or not introduced fish.
The model seems to run fine, but I have trouble in obtaining the
expected probabilities for each size category in lakes with and
without introduced fish... Anybody can help me out?
your help would be greatly appreciated!
cheers,
Achaz von Hardenberg
Gran Paradiso National PArk. Italy
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