I am trying to run an analysis and I its unclear to me if I have to include random factors.
I am working with microbiome data and have OTU tables (e.g. list of species per sample) for 5 different groups/samples. I also have measurements for the home range overlap between these 5 groups. I am interested in the question if range overlap predicts the OTU overlap. So do for instance groups that overlap a lot have more similar OTU's.
I have 5 groups and will have to compare 10 pairs:
A - B, A - C, A - D, A - E, B - C, B - D, ect.
My question is if I can run a simple linear model like:
lm(otu_sharing ~ range_sharing)
or do I need to control for the fact that I use the same groups multiple time by including them as a random factor:
lmer(otu_sharing ~ range_sharing + (1|group1) + (1|group2))