Recommendations
Avoid complex sentence structures. They are less easy to understand quickly understanding them requires more cognitive effort than simple sentences.
Complexity is defined by:
- the number of clauses in a sentence, the more clauses the more complex it is
- word order – how easy or difficult it is for the brain to parse a phrase, that is to recognise, group and take meaning from words that together convey meaning
Word order example:
a) "The red fox jumped over the gate."
b) "The fox, which was red, over the gate jumped."
Sentence a) is easier to understand than sentence b). Both are grammatically correct.
Usability evidence
'How the brain attunes to sentence processing: Relating behavior, structure, and function', A. Fengler, L. Meyer, A. D. Friederici, National Center for Biotechnology Information
'Functional Analysis of Clause Complex in the Language of News Websites Texts: A Comparative Study of Two Articles', F. M. S. Eid, International Journal of Scientific and Research Publications, Volume 6, Issue 6, June 2016
As well as a short sentence length, choosing a non-complex sentence structure is important for plain English and clear language.
This Beta discussion took place in Slack: https://readabilityguidelines.slack.com/messages/CDE1RGL3Z/details. Joining link: https://bit.ly/2D0OW1F Key evidence is posted on the relevant wiki Article pages – see also plain English.