[hnaa]

Amateur Shakespearean here. I've often wondered why these statistical approaches don't look for stylistic signatures. For instance, several plays are linked by their use of doubles (in Hamlet, this scales from "too, too solid flesh," up to the running joke on the interchangeability of Rosencrantz and Guildenstern). Shakespeare also seems to be especially fond of puns on "bear" and "born" -- the "to be or not to be" monologue has three or four of these. There are also ways in which scenes repeat their designs -- 1.2 of Hamlet is similar in some ways to 3.2 of Julius Caesar, etc.

[basch]

I imagine two things that make simple analysis harder.

1) once an author has a sufficient library, hiring a team to emulate them is easier (Tom Clancy, Hanz Zimmer.)

2) if in a collaboration, a partner could write a skeleton or first draft, and the main author could edit and fill in the cracks. Conversely they could write scattered sentences and have their partner flesh out filler.