Table 2.
Fit of all the factor models tested in the study.
| Model | χ2 | df | RMSEA (90% CI) | CFI | TLI | AIC |
|---|---|---|---|---|---|---|
| WISC/Four-factor | 107.42∗∗∗ | 29 | 0.058 (0.046–0.070) | 0.976 | 0.96 | 38185 |
| WISC/Higher order factor | 137.84∗∗∗ | 31 | 0.065 (0.054–0.076) | 0.967 | 0.95 | 38212 |
| WISC/Bifactor | 116.95∗∗∗ | 27 | 0.064 (0.052–0.076) | 0.972 | 0.94 | 38199 |
| CHC/Five-factor | 79.85∗∗∗ | 24 | 0.054 (0.041–0.067) | 0.983 | 0.97 | 38168 |
| CHC/Higher order factor | 135.01∗∗∗ | 29 | 0.067 (0.056–0.079) | 0.968 | 0.95 | 38213 |
All χ2 goodness-of-fit tests were statistically significant at p < 0.001. CFI, comparative fit index; CI, confidence interval; RMSEA, root mean square error of approximation; TLI, Tucker Lewis Index; AIC, Akaike information criterion. For the WISC/bifactor model, the factor pattern coefficients of the subtests within WM and PS (Coding and Symbol Search) were constrained to be equal. Without these modifications the bifactor model showed non-identification. ∗∗∗p < 0.001.