Hello,

I've read in many other posts (ex: this and this) that the order of the variables matters when inputting the formula for the Adonis test. I have a beast of a formula (9 variables) and I'm not sure of best practices on how to order the variables.

From the first linked post, I understand that whatever variance isn't explained in variable 1 is passed down to the next term and so forth. Does that mean I should stack my variables to have the ones responsible for the most variance at the beginning?

For example, one of my human microbiome study variables is "relatedness," i.e. whether patients are first degree relations (there are 137 families total). It's well established that families/cohabitants will have more similar microbiomes, so should I list that first/early in my formula?

I have tested this theory a little and (with my data at least) if I run the formula with relatedness toward the end most everything before it is statistically significant, but if I run it was the first term nothing is statistically significant besides relatedness. Relatedness is basically stead with its R^2 value, 67% and 71% respectively.

I'm trying to determine the most unbiased way to run the test. Any and all thoughts/feedback would be greatly appreciated!

Thanks,

Samantha