This repository contains the raw dataset associated to the scientific article "Stable psychological traits predict psychological perceived stress to COVID-19 outbreak”, by L. Flesia, V. Fietta, B. Segatto, M. Monaro. Data are contained in the excel file and organized as follows: - the entire dataset used by the authors to perform statistical analysis - the training set used by the authors to train and validate ML models - the test set used by the authors to test the ML models The "Legend" file contains the description of each variable in the excel file. The step by step instructions to replicate the results of ML classification models, which are reported in the paper, including two .arff files containing the training and test set od data that can be directly run in WEKA software 3.9. The "COVID-19 QUESTIONNAIRE" file contains the English version of the questions administered to participants.