European Portuguese Validation of the System Usability Scale (SUS)

The System Usability Scale (SUS) is a widely used self-administered instrument for the evaluation of usability of a wide range of products and user interfaces. The principal value of the SUS is that it provides a single reference score for participants’ view of the usability of a product or service. This paper presents the translation, cultural adaptation and a contribution to the validation of the European Portuguese version of SUS. The conducted work comprised two phases, the scale translation, and the scale validation. The first phase resulted in a European Portuguese version equivalent to the original in terms of semantic and content. The second phase involved the assessment of the validity and reliability of the scale. The instrument has construct validity as it presents a high and significant correlation with other two usability metrics, the Post-Study System Usability Questionnaire (PSSUQ) (r = 0.70) and a general usability question (r = 0.48). The reliability results show less than satisfactory ICC values (ICC = 0.36), however the percentage of agreement is satisfactory (76.67%). Further studies are needed to investigate the reliability of the Portuguese version.