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Cogn Process. 2009 Aug;10(3):193-7. doi: 10.1007/s10339-009-0268-9. Epub 2009 Jun 30.

On the dimensionality of the System Usability Scale: a test of alternative measurement models.

Author information

1
ECoNA, Interuniversity Centre for Research on Cognitive Processing in Natural and Artificial Systems, University of Rome 'La Sapienza', Rome, Italy. simone.borsci@uniroma1.it

Abstract

The System Usability Scale (SUS), developed by Brooke (Usability evaluation in industry, Taylor & Francis, London, pp 189-194, 1996), had a great success among usability practitioners since it is a quick and easy to use measure for collecting users' usability evaluation of a system. Recently, Lewis and Sauro (Proceedings of the human computer interaction international conference (HCII 2009), San Diego CA, USA, 2009) have proposed a two-factor structure-Usability (8 items) and Learnability (2 items)-suggesting that practitioners might take advantage of these new factors to extract additional information from SUS data. In order to verify the dimensionality in the SUS' two-component structure, we estimated the parameters and tested with a structural equation model the SUS structure on a sample of 196 university users. Our data indicated that both the unidimensional model and the two-factor model with uncorrelated factors proposed by Lewis and Sauro (Proceedings of the human computer interaction international conference (HCII 2009), San Diego CA, USA, 2009) had a not satisfactory fit to the data. We thus released the hypothesis that Usability and Learnability are independent components of SUS ratings and tested a less restrictive model with correlated factors. This model not only yielded a good fit to the data, but it was also significantly more appropriate to represent the structure of SUS ratings.

PMID:
19565283
DOI:
10.1007/s10339-009-0268-9
[Indexed for MEDLINE]

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