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Table 2 Confirmatory factor analysis fit indices and model-based omega coefficients

From: Improving the measurement of alexithymia in autistic adults: a psychometric investigation of the 20-item Toronto Alexithymia Scale and generation of a general alexithymia factor score using item response theory

Index TAS-20 Bifactor: SPARK TAS-20 Bifactor: HPP 11-item Bifactor: SPARK 11-item Bifactor: HPP
Model FIT INDICEs     
χ2 (df)a 590.6 (145) 669.9 (145) 151.6 (33) 124.0 (33)
CFIcML 0.924 0.900 0.970 0.978
TLIcML 0.900 0.869 0.951 0.963
RMSEAcML [90% CI] 0.072 [0.066, 0.078] 0.086 [0.081, 0.092] 0.080 [0.069, 0.092] 0.068 [0.056, 0.079]
SRMRu [90% CI] 0.036 [0.033, 0.004] 0.051 [0.047, 0.056] 0.020 [0.017, 0.024] 0.019 [00.015, 0.023]
WRMR 1.119 1.565 0.768 0.699
|Residuals| > 0.1 2.60% 8.90% 0% 0%
Largest residual 0.149 0.225 0.084 0.055
Bifactor coefficients     
ωT/ωH 0.912/0.773 0.914/0.741 0.929/0.861 0.925/0.952
ωS/ωHS (DIF) 0.906/0.162 0.880/0.224 0.913/0.087 0.892/0.071
ωS/ωHS (DDF) 0.854/0.145 0.803/0.120 0.800/0.163 0.839/0.223
ωS/ωHS (EOT) 0.451/0.300 0.512/0.307
ωS/ωHS (REV) 0.559/0.441 0.692/0.689
  1. Fit indices that above the a priori cutoffs for acceptable model fit (CFI/TLI > 0.95, RMSEA < 0.06, SRMR < 0.08, WRMR < 1, all residuals < 0.1) are presented in bold. TAS = Toronto Alexithymia Scale; SPARK = Simons Powering Autism Research Knowledge; HPP = Human Penguin Project; CFIcML = comparative fit index (categorical maximum likelihood estimation); TLIcML = Tucker–Lewis Index (categorical maximum likelihood estimation); RMSEAcML = root mean square error of approximation (categorical maximum likelihood estimation); SRMRu = population-unbiased standardized root mean square residual; WRMR = weighted root mean square residual; ωT = omega total (composite reliability of total score); ωH = omega hierarchical (proportion of total score variance accounted for by general factor); ωS = omega subscale (composite reliability of subscale score); ωHS = omega hierarchical subscale (proportion of subscale score variance accounted for by specific factor); DIF = difficulty identifying feelings; DDF = difficulty describing feelings; EOT = externally oriented thinking; REV = reverse-coded item method factor
  2. aAll p values < 0.001