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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