Usability Scores

One of the key questions we get from clients is "how usable is our product?" There are various ways this can be answered, providing scores for various metrics (average task time, average user satisfaction rating, etc) is one option, but sometimes a single usability score is more helpful. After looking through current practices in the industry and current work in academia, we began to provide our mobile device clients with System Usability Scale (SUS) scores. The score is generated by participants completing a weighted questionnaire at the end of the test session, answering questions regarding their experience with the device.

We are currently looking into using the Single Usability Metric (SUM) to attach a value to a device's usability. This metric provides a usability score based on task completion times, error rates, and user satisfaction.

Each score has advantages and drawbacks, but when applied responsibly to a project can result in added value for our client.