TY - JOUR
T1 - Dimensionality of the system usability scale among professionals using internet-based interventions for depression
T2 - a confirmatory factor analysis
AU - Mol, Mayke
AU - van Schaik, Anneke
AU - Dozeman, Els
AU - Ruwaard, Jeroen
AU - Vis, Christiaan
AU - Ebert, David D
AU - Etzelmueller, Anne
AU - Mathiasen, Kim
AU - Moles, Bárbara
AU - Mora, Teresa
AU - Pedersen, Claus D
AU - Skjøth, Mette Maria
AU - Pensado, Luisa Peleteiro
AU - Piera-Jimenez, Jordi
AU - Gokcay, Didem
AU - Ince, Burçin Ünlü
AU - Russi, Alessio
AU - Sacco, Ylenia
AU - Zanalda, Enrico
AU - Zabala, Ane Fullaondo
AU - Riper, Heleen
AU - Smit, Jan H
PY - 2020/5/12
Y1 - 2020/5/12
N2 - 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.
AB - 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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U2 - 10.1186/s12888-020-02627-8
DO - 10.1186/s12888-020-02627-8
M3 - Article
C2 - 32398111
SN - 1471-244X
VL - 20
SP - 218
JO - BMC Psychiatry
JF - BMC Psychiatry
IS - 1
M1 - 218
ER -