Ease of use and medical devices - Perceptions and reality

Abstract

The aim of this study was to examine the relationship between objective task performance outcomes and subjective usability ratings measured during usability evaluations. Likert-type rating scales are often used to support claims of usability. However, there is no published evidence of there being any correlation with more objective task outcome scores. A meta-analysis of usability study data was performed to compare objective and subjective usability scores. The data used was extracted from two formative and four summative studies of medical devices undertaken between 2011 and 2014. All the participants were observed while using a device and then asked to rate ease of use using a Likert scale. The analysis showed a weak correlation between perceived difficulty and task failure scores (r2 = 0.271, p < 0.001). In conclusion, the results suggest that perceived ease of use is not a robust measure of true usability.