Table 2.
Loadings, correlation with sum score and fit indices of the three latent variable models in the calibration sample
| Unidimensional model | Two-dimensional model | Bi-factor model | |||||
|---|---|---|---|---|---|---|---|
| Item | Cognitive-affective | Somatic factor | General factor | Cognitive-affective | Somatic factor | ||
| Loadings | PHQ-9 1 | 0.88 (0.01) | 0.86 (0.01) | 0.84 (0.01) | 0.11 (0.02) | ||
| PHQ-9 2 | 0.91 (0.01) | 0.89 (0.01) | 0.88 (0.01) | 0.35 (0.03) | |||
| PHQ-9 3 | 0.70 (0.03) | 0.67 (0.01) | 0.60 (0.01) | 0.33 (0.02) | |||
| PHQ-9 4 | 0.81 (0.02) | 0.82 (0.01) | 0.73 (0.01) | 0.34 (0.02) | |||
| PHQ-9 5 | 0.73 (0.03) | 0.72 (0.01) | 0.64 (0.01) | 0.33 (0.02) | |||
| PHQ-9 6 | 0.85 (0.02) | 0.81 (0.01) | 0.79 (0.01) | 0.17 (0.03) | |||
| PHQ-9 7 | 0.81 (0.02) | 0.75 (0.01) | 0.77 (0.01) | −0.18 (0.03) | |||
| PHQ-9 8 | 0.77 (0.02) | 0.72 (0.01) | 0.75 (0.01) | −0.28 (0.03) | |||
| PHQ-9 9 | 0.82 (0.02) | 0.76 (0.01) | 0.75 (0.01) | 0.12 (0.03) | |||
| correlation with PHQ-9 Sum Score | 0.97 | 0.97 | 0.97 | 0.97 | 0.18 | 0.42 | |
| Model Fit | Robust chi-square | 3447.80 | 2971.95 | 2720.10 | |||
| Degree of freedom | 1186 | 1185 | 1158 | ||||
| p value | <0.001 | <0.001 | <0.001 | ||||
| CFI | 0.940 | 0.953 | 0.959 | ||||
| RMSEA (95% CI) |
0.092 (0.088; 0.095) |
0.082 (0.078; 0.085) |
0.077 (0.073; 0.081) |
||||
| SRMR | 0.083 | 0.100 | 0.097 | ||||
CFI: comparative fit index, RMSEA: root mean square error of approximation, SRMR: standardized root mean square residual.