Quantifying Usability via Task Flow-Based Usability Checklists for User-Centered Design

In this study, we investigated the effectiveness of a method to quantify the overall product usability using an expert review. The expert review involved a general-purpose task flow-based usability checklist that provided a single quantitative usability score. This checklist was expected to reduce rating variation among evaluators. To confirm the effectiveness of the checklist, two experiments were performed. In Experiment 1, the usability score obtained using the proposed checklist was compared with traditional usability measures (task completion ration, task completion time, and subjective rating). The results demonstrated that the usability score obtained using the proposed checklist shows a tendency similar to that of the traditional measures. In Experiment 2, we investigated the inter-rater agreement of the proposed checklist by comparing it with a similar method. The results demonstrate that the inter-rater agreement of the proposed task flow-based usability checklist is greater than that of structured user interface design and evaluation