Dimensionality of the system usability scale among professionals using internet-based interventions for depression: a confirmatory factor analysis

Mol M, van Schaik A, Dozeman E, Ruwaard J, Vis C, Ebert D, Etzelmueller A, Mathiasen K, Moles B, Mora T, Pedersen CD, Skjøth MM, Pensado LP, Piera-Jimenez J, Gokcay D, Ince BÜ, Russi A, Sacco Y, Zanalda E, Zabala AF, Riper H, Smit JH (2020)


Publication Type: Journal article

Publication year: 2020

Journal

Book Volume: 20

Pages Range: 218-

Journal Issue: 1

DOI: 10.1186/s12888-020-02627-8

Abstract

BACKGROUND: The System Usability Scale (SUS) is used to measure usability of internet-based Cognitive Behavioural Therapy (iCBT). However, whether the SUS is a valid instrument to measure usability in this context is unclear. The aim of this study is to assess the factor structure of the SUS, measuring usability of iCBT for depression in a sample of professionals. In addition, the psychometric properties (reliability, convergent validity) of the SUS were tested. METHODS: A sample of 242 professionals using iCBT for depression from 6 European countries completed the SUS. Confirmatory Factor Analysis (CFA) was conducted to test whether a one-factor, two-factor, tone-model or bi-direct model would fit the data best. Reliability was assessed using complementary statistical indices (e.g. omega). To assess convergent validity, the SUS total score was correlated with an adapted Client Satisfaction Questionnaire (CSQ-3). RESULTS: CFA supported the one-factor, two-factor and tone-model, but the bi-factor model fitted the data best (Comparative Fit Index = 0.992, Tucker Lewis Index = 0.985, Root Mean Square Error of Approximation = 0.055, Standardized Root Mean Square Residual = 0.042 (respectively χ2diff (9) = 69.82, p < 0.001; χ2diff (8) = 33.04, p < 0.001). Reliability of the SUS was good (ω = 0.91). The total SUS score correlated moderately with the CSQ-3 (CSQ1 rs = .49, p < 0.001; CSQ2 rs = .46, p < 0.001; CSQ3 rs = .38, p < 0.001), indicating convergent validity. CONCLUSIONS: Although the SUS seems to have a multidimensional structure, the best model showed that the total sumscore of the SUS appears to be a valid and interpretable measure to assess the usability of internet-based interventions when used by professionals in mental healthcare.

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APA:

Mol, M., van Schaik, A., Dozeman, E., Ruwaard, J., Vis, C., Ebert, D.,... Smit, J.H. (2020). Dimensionality of the system usability scale among professionals using internet-based interventions for depression: a confirmatory factor analysis. BMC Psychiatry, 20(1), 218-. https://dx.doi.org/10.1186/s12888-020-02627-8

MLA:

Mol, Mayke, et al. "Dimensionality of the system usability scale among professionals using internet-based interventions for depression: a confirmatory factor analysis." BMC Psychiatry 20.1 (2020): 218-.

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