Hi,

I fitted a Gamma GLMER to predict the amount of organic matter (OM) stored in plants using plant area (PA) and species as fixed effects. I collected the plants in different trees and different forests, thus I included these factors as random effects (tree within forest).

This is the code that I used to fit the model

glmer(OM~ PA + Species + (1|Site:Tree), family = Gamma(link = "log"))

Now I would like to present the statistical model and I am following the protocol proposed by Zuur and Ieno (2013). I used the following equation to describe the model.

OMijk ~ Gamma (µijk)

E(OMijk) = µijk

var(OMijk) = μ2/ν

Sitei ~ N(0,σ2site)

Treej ~ N(0,σ2tree)

log(µijk) = PAijk + Speciesijk + Sitei + Treej

I think this equation does not reflect the nested structure of the random effects.

It is the presentation of my model correct?

Thanks