This repository contains the anonymised dataset and analysis files used in the study. The materials include: The anonymised raw dataset in .omv format (Jamovi file), containing all lexical and syntactic complexity measures analysed in the study, as well as text quality scores assigned by human raters and GPT-4o. The statistical analysis files used to conduct descriptive statistics, ANOVA tests, correlation analyses, and regression models reported in the article All personal identifiers have been removed to ensure participant anonymity.