Investigating the Authenticity of Pliny the Younger’s Letter to Trajan Concerning the Christians

Book 10 was divided in 15 subsections having the same lenght of PT (i.e. approximately 3000 characters) and they show a relatively homogeneous stylistic behavior in all the considered models.
Models vary modifying the size of the n-grams and the length of the profile of known authorship. Varying the parameters (i.e. the models) would help to identify that model more able to catch stylistic differences between different authors. For fragments having the same author these differences should be less relevant, in fact so it is for the 15 Plinian subsections. Instead from my analysis it’s evident that Ep.96 changes significantly its behavior varying the models (as fragments of Cicero or Seneca). In 4 models out of 6 Ep.10.96 is outside the 99% confidence zone. We are not speaking of minor differences. Differences in topic can hardly explain such a difference. In Book 10 we have one global topical pattern (questions about the administrative affairs in Ponto and Bitinia) common to all the letters of Book 10 (including Ep.96.10) and as many local topics as the numbers of the letters. So should we expect a different stylistical behavior only in Ep.96?