Sentence Length In U.S. Presidential Inaugural Addresses Dropped 2.5 Times Over 2 Centuries, UrFU Scientists Say

10:29, January 21, 2021

It turned out median length dropped linearly from 45-50 to around 20 words per sentence

Yesterday, 46th President of the U.S.A. Joseph R. Biden jr. took the oath of office. One could say that his inaugural address to the nation was in terms more or less standard, though emotional. Biden’s speech wound up being 21 minutes and 18 seconds long. For comparison, President Trump’s inaugural speech, focusing on “American carnage,” lasted just 16 minutes and 14 seconds and was 1,433 words long (NPR) . The phrases used by the freshly inaugurated President were not long. 

Throughout the address Biden used one-two-words-long sentences to put additional emphasis on problematic issues. (e.g. sort of paraphrasing FDR's 'Four Freedoms' here: 'What are the common objects we love that define us as Americans? I think I know. Opportunity. Security. Liberty. Dignity. Respect. Honor' or the longest sentence: 'So now, on this hallowed ground where just days ago violence sought to shake this Capitol's very foundation, we come together as one nation, under God, indivisible, to carry out the peaceful transfer of power as we have for more than two centuries' ). 

This goes well into the conclusive frame of the statistical analysis carried out  by UrFU scientists.          

А recent article by N. L. Tsizhmovska and L. M. Martyushev (from the Ural Federal University in Russia) titled Analysis of Sentence Lengths in Public Speaking which answers it. That article appeared in an American Institute of Physics publication titled The VII International Young Researchers’ Conference – Physics, Technology, Innovations (PTI-2000).

They looked at all 58 speeches from 1789 to 2017. From 1789 to 1809 the mean (average) sentence length in a speech was about 50 words, while from 1997 to 2017 it had dropped to just about 20 words. It dropped linearly, as did the median. They also concluded that sentence lengths obeyed a Weibull distribution. 

"It was found that 44 texts have unimodal distributions and 14 texts have bi- or multi- modal distributions. There are eight multimodal distributions in the XIX century and five ones in the XX century," states the article. 

Based on the analysis of the inaugural speeches of US presidents for 228 years, two main results were obtained:

1. The sentence length over time reduces linearly. The rate of this decrease, approximately 0.14±0.03 words per year (about 14 words per 100 years).
2. The distribution of sentence lengths obeys the Weibull distribution with high probability. As well known, distributions of extreme values are subject to the Weibull distribution. Therefore, the result allows us to put forward a hypothesis that when composing sentences, the speaker tries to choose the minimum possible sentence length from an array of sentences with approximately one content, i.e. he is guided by the principle that the listener must spend the least effort (time) when perceiving speech.