TABLE 5

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

Usability MeasureWave 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).