3. A bit more on 'multidimensional analysis," for the curious. The goal of this method is to model stylistic variation in a database of text. To do that, a computer program takes a large amount of text data and figures out which of dozens of grammatical structures-like types of verbs, questions, superlatives, and plenty more---are most common in each of the individual texts dataset. Finally, the analysis identifies patterns across groups of grammatical forms, which taken together can group the texts into different "'dimensions." Looking at the dimensions that account for the biggest variation in grammar within the dataset can explain the differences in style over time.
(https://qz.com/1153080/trump-tweets-analyzed-by-linguists-reveal-five-characteristics/)