Table 3.

A summary of the analysis of interview data exploring the usability of Motus. The analysis is based on verbatim transcriptions of semistructured exit interviews. Data were assigned to the predefined codes of learnability, efficiency, memorability, safety, and satisfaction (each a subconstruct of usability [13]).

Sub construct	Analysis	Evaluation
Learnability	All participants found the app easy to navigate All participants found the instructions easy to follow	Easy to learn, but attachment instructions could be improved.
Efficiency	3 out of 12 wondered how long the work and sleep time process would take 11 out of 12 used less than 3 minutes on sleep and work time 8 out of 12 had time issues with uploading data	Clarification of the expected daily time burden would be beneficial and the speed of data upload time needs to be improved
Memorability	All participants registered work and sleep time for 7 days 8 out of 12 typically registered hours each morning	Functionality was easy to remember over several days
Safety	4 out of 12 participants found the entry of work and sleep hours confusing	Few errors, mostly related to the entry of atypical work and sleep hours. Issues with the adhesive patch were also noted toward the end of the measurement week (eg, itching, becoming loose)
Satisfaction	10 out of 12 would take part in measurements again 6 out of 12 felt engaged throughout the measurements (n=6)	The app was subjectively pleasing, although a few participants desired more frequent and detailed feedback on their level of activity. Most did not notice wearing the sensor.