TABLE 5.

Task Completion, Mental Workload, and Ease of Use During App Usability Testing: SUS and NASA TLX Scores

Usability Measure	Wave 1 (n = 2)	Wave 2 (n = 7)	Wave 3 (n = 5)
SUS, mean (range)	72.5 (70.0–75.0)	76.1 (62.5–92.5)	76 (60.0–100.0)
NASA TLX, mean (range)	33.8 (29.2–38.3)	23.8 (5.0–37.5)	31.7 (20.8–46.7)

In the SUS, participants rate the degree to which they agree or disagree with each of 10 statements. Scores are aggregated and transformed into a total score from 0 (low usability) to 100 (high usability). In the NASA TLX, participants evaluate mental workload in 6 dimensions (mental demand, physical demand, temporal demand, performance, effort, and frustration.) Scores are aggregated and transformed into a total score from 0 (low workload) to 100 (high workload).