If you took 30 people, and randomly put them into 15 pairs, then the probability that Person A would be paired with Person Z is 1⁄29. Person A is equally likely to be paired with any of the 29 other people.
If you took 15 women & 15 men, and randomly put them into 15 woman-man pairs, then the probability that Woman A would be paired with Man Z is 1⁄15. Woman A is equally likely to be paired with any of the 15 men.
The stylometrics analysis resembles the former situation, with p=1/29. The script could’ve been paired with any of the 29 other items.
If you took 30 people, and randomly put them into 15 pairs, then the probability that Person A would be paired with Person Z is 1⁄29. Person A is equally likely to be paired with any of the 29 other people.
If you took 15 women & 15 men, and randomly put them into 15 woman-man pairs, then the probability that Woman A would be paired with Man Z is 1⁄15. Woman A is equally likely to be paired with any of the 15 men.
The stylometrics analysis resembles the former situation, with p=1/29. The script could’ve been paired with any of the 29 other items.