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

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.

Acculturation and suicidal ideation among Turkish migrants in the Netherlands✰.

More suicidal ideation and higher rates of attempted suicide are found in Turkish people when compared with the general population in Europe. Acculturation processes and related distress may explain an elevated risk of suicide. The current study investigates the association between acculturation and suicidal ideation among Turkish migrants in the Netherlands. The mediating effect of hopelessness and moderating effect of secure attachment are also examined. A total of 185 Turkish migrants living in the Netherlands were recruited through social media and through liaison with community groups. They completed an online survey including validated measures of suicidal ideation, hopelessness, acculturation and attachment style. Mediation and moderation analyses were tested using bootstrapping. Higher participation was associated with less hopelessness and less suicidal ideation. Greater maintenance of one's ethnic culture was associated with higher hopelessness and higher suicidal ideation. Greater participation was associated with less suicidal ideation particularly amongst those with less secure attachment styles. Turkish migrants who participate in the host culture may have a lower risk of developing suicidal thinking. Participation may protect against suicidal thinking, particularly among those with less secure attachment styles.