
Hi everyone
 
I know that lmer can handle cross-classified random effects, but can it handle random effects 
involving multiple membership as well? My problem is this: I am modelling the number of visits 
made by different individuals at every feeder they visit daily. I have three random effects: 
individual, feeder and date. There is multiple membership in terms of feeders and dates 
and an individual can potentially be seen at many different feeders which can change everyday. 
To make it simpler, here is an example of the data:
 
Individual           Date          Feeder          Number of visits 
       1                   155              A                           13
       1                   155              B                           34
       1                   157              A                           76
       2                   155              A                           87
       2                   156              B                           34
       2                   157              C                           23
       3                   155              A                             3
       3                   155              D                         123
       3                   156              D                           12
       3                   157              A                           56
       3                   157              E                           24
       3                   168              A                          45
       3                   168              B                            6
       3                   168              C                          78
 
If I am not interested in date as a fixed effect, I have to put it in the model as a random effect 
and I’m wondering if specifying the model like this in lmer is the thing to do (not interested in 
varying slopes yet):
 
fixed effects + (1|individual) + (1|feeder) + (1|date)         
 
However, if I am interested by the date as a fixed effect, do I have to specify it in the random 
effects as well to indicate that the repeated measures on individuals are related to feeders and 
dates? If so, does it have to be specified in any special way?
 
Thanks in advance
Sincerely,
Francois Rousseu
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