[R-sig-ME] GAMMs: difference smooths in itsadug

[Sebastian Sauppe]

Dear list members,

I have a question on the treatment of random effects in plotting difference smooths for GAMMs with the package itsadug.

I am modelling the time course of binomial data with mgcv::bam. The simplified formula is: cbind(success, failure) ~ 1 + s(Time, by = Condition) + s(Subject, Time, bs = „fs“) + s(Item, Time, bs = „fs“). The two factor smooths are supposed to account for the random effects of participants and stimuli in my experiments.

I would like to use itsadug::plot_diff() to visualize how the two conditions differ over time. However, I am not quite sure what the rm.ranef argument argument of this function does. What I basically want to do is to look at the difference the way one would look at a fixed effect in an GLMER model, i.e., looking at the fixed effect of the interaction of Time:Condition after the variance that can be ascribed to random effects of subjects and items have been accounted for. Would for this rm.ranef=TRUE or rm.ranef=FALSE be the right option?

Kind regards,
Sebastian

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Dr. Sebastian Sauppe
Department of Comparative Linguistics, University of Zurich
Homepage: https://sites.google.com/site/sauppes/ <https://sites.google.com/site/sauppes/>
Twitter: @SebastianSauppe <https://twitter.com/SebastianSauppe>
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ResearchGate: http://www.researchgate.net/profile/Sebastian_Sauppe <http://www.researchgate.net/profile/Sebastian_Sauppe>
ORCID ID: http://orcid.org/0000-0001-8670-8197 <http://orcid.org/0000-0001-8670-8197>

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