The reference group in trend test

[yd-x]

Hi Lin,

Thank you for developing this helpful and user-friendly package!

I have a quick question. When doing trend test, how does ancombc2 set the reference group? I guess it uses the first group as default. Before doing ancombc2, I should use the factor function to put the reference group as the first level.

Is that correct?

Thank you in advance! Yuandong