A Readability Analysis of Campaign Speeches from the 2016 US Presidential Campaign

Introduction The goal of this report is to assess the readability of the campaign speeches of five presidential candidates in the 2016 US presidential race and to examine their evolution over time and according to the type of speech. Readability can be defined here as the reading level, from grade 1 to grade 12, of a document. It is determined by looking at the lexical contents and the grammatical structure of the sentences in a document. It is based on the observation that some words (and grammatical structures) appear with greater frequency at one grade level than another. For example, we would expect that we could see the word " win " fairly frequently in third grade documents while the word " successful " would be more frequent in, say, seventh grade documents. We would not see dependent clauses very often at the second grade level whereas they would be quite frequent at the seventh grade level. For this analysis, we use a readability model, REAP, that was developed for vocabulary at by Collins-Thompson and Callan (2004) and further developed for grammar by Heilman et al (2006, 2007). It is based on a database of sets of texts, one set for each grade level. Most of the texts come from student-written texts that teachers have published on their websites, noting the grade that each represents. The lexical reading difficulty measure is based on the smoothed individual probabilities of words occurring at each reading level. For example, the word, determine, was predictive of Grade 11 text, and was more predictive of high school-level text than lower-level text. The grammar reading difficulty measure is based on the one-to three-level depth parse trees of the sentences. This means that the measure is based on typical grammatical constructions in sentences of each grade level.