WAIS-III measurement invariance: Data from Estonian standardization

Area of Science:

• Psychometrics
• Cognitive Assessment

Background:

• Measurement invariance (MI) is crucial for comparing individuals across groups using psychological instruments.
• The Estonian version of the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) was recently adapted.

Purpose of the Study:

• To evaluate the measurement invariance (MI) of the Estonian WAIS-III across sex, age groups, and educational levels.
• To assess if the WAIS-III measures the same psychological constructs consistently across these demographic variables.

Main Methods:

• Confirmatory factor analysis (CFA) was used to establish the baseline factor model for the Estonian WAIS-III.
• Multi-group confirmatory factor analysis (MG-CFA) was applied to test for measurement invariance across sex, age, and education.

Main Results:

• The four-factor model was supported by CFA.
• Partial measurement invariance was found across sexes and age groups, with significant mean differences noted.
• Measurement invariance was not tenable across educational levels, indicating potential differences in test interpretation.

Conclusions:

• The Estonian WAIS-III demonstrates partial measurement invariance across sex and age groups, supporting its use for comparisons within these demographics.
• The lack of invariance across educational levels suggests caution when interpreting WAIS-III scores for individuals with different educational backgrounds.