Classification Accuracy of Sequentially Administered WAIS-IV Short Forms

Area of Science:

• Psychometrics
• Neuropsychological Assessment
• Clinical Psychology

Background:

• The Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) is a comprehensive measure of adult intelligence.
• Developing efficient short forms (SFs) is crucial for clinical settings to reduce administration time while maintaining diagnostic utility.

Purpose of the Study:

• To evaluate the effectiveness of different Wechsler Adult Intelligence Scale-Fourth Edition short forms (WAIS-IV SFs) in identifying subnormal intelligence.
• To determine optimal WAIS-IV SF configurations for accurate classification of intellectual impairment.

Main Methods:

• One hundred twenty-two patients completed the full WAIS-IV.
• Two analyses were conducted using Full-Scale IQ (FSIQ) cutoffs of ≤69 and ≤79 to define intellectual impairment.
• Classification accuracy statistics, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), were calculated for 2-, 3-, 4-, and 5-subtest WAIS-IV SFs.

Main Results:

• All WAIS-IV SFs exceeded the base rate of subnormal intelligence, with hit rates between 84% and 95%.
• The FSIQ cutoff of ≤69 showed poor sensitivity but excellent specificity, PPV, and NPV for all SF lengths.
• The FSIQ cutoff of ≤79 demonstrated strong to excellent sensitivity, specificity, PPV, and NPV for 3-, 4-, and 5-subtest SFs.

Conclusions:

• WAIS-IV short forms are effective tools for ruling out subnormal intelligence.
• The 3-, 4-, and 5-subtest WAIS-IV SFs with an FSIQ cutoff of ≤79 offer a strong balance of sensitivity and specificity for identifying intellectual impairment.