Do you have any personal knowledge of how this analysis was done? I know of a piece of writing that I have long wished to see put through this same sort of process to determine authorship of it.
MASSIVE work over years! It’s preparing the data to go through programs and then putting the results through statistical programs. The programs that are out there have the worst human interfaces you can imagine. I was in the User Interface Institute at IBM Research, which is one of the reason we were able to provide Mac with the level of data that let him dig down to China.
It was a retired professor in New Zealand, MacDonald P. Jackson, who did the computer study, and there's also a wikipedia page about him.