The following results were reported at the 2001 IHM-HCI conference in Lille, France.

The Global Usability Score (GUS) exhibits a high degree of reliability, technically measured using Cronbach's Alpha coefficient, with Alpha = 0.90. This coefficient usually ranges from 0.00 (poor reliability) to 1.00 (high reliability).

The five sub-scales, being smaller, have lower intrinsic Alpha coefficients, but when adjusted for size, are comparable with the Global scale:

Scale Reliability
Raw Adj.
Attractiveness 0.640 0.899
Controllability 0.690 0.918
Efficiency 0.630 0.895
Helpfulness 0.700 0.921
Learnability 0.740 0.934
Global 0.900 -

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