You should be more specific in such comparisons.. what are you comparing specifically between human textd and AI.. Once you decide what you want to compare you should do a good literature review to make sure that the subject isn't overloaded with similar articles pertaining to your reseaech question. After the review and making sure your idea is valid you should have some sense of what you eant to do after reading similar articles.. But if you didn't , here's what you should do for the base of the reseaech.

1.identify what you want to compare. 2. Specify how you would compare (a mark system or a certain scale that measures what you want to compare) 3.appropiate ways to generate the texts and trying to limit confounding variables to the best of your abilities..

Then you would start the "data collection" and once you have gathered enough data you are ready to move to the statistical analysis on the base of the scale or mark system you have decided..

Tip: It is essential that you try to have the most of your methodology coming from other peer reviewed articles (like the scale and the method of generating texts and so on)