Hello, thank you so much for developing such a useful tool!
I am trying to use Maaslin for differential abundance analysis. Specifically, my input_data would be OTU counts, and the input_metadata contains a binary group label and some other covariates, and the primary interest is to test whether the microbiome composition (characterized by OTU abundance) differs across the two groups.
I understand that Maaslin outputs significant associations (if any) and some relevant statistics, like q-values of OTU-metadata pairs. I am wondering is there a global test statistic, characterizing whether there is ANY difference in the OTU abundance across the two groups? I suppose I can say there is such difference if there is at least one pair of significant OTU-group association, but I’d like to learn about whether there are other options, especially something like a “global” p-value.
Hopefully this makes sense. Thank you so much 
The linear models used in Maaslin2 wouldn’t be appropriate for such a comparison, you probably want PERMANOVA.