Psychometric qualities of a tetrad WAIS-III short form for use in individuals with mild to borderline intellectual disability.

Objective: To investigate the reliability and validity of a Wechsler Abbreviated Scale of Intelligence-based Wechsler Adult Intelligence Scale - third edition (WAIS-III) short form (SF) in a sample of individuals with mild to borderline intellectual disability (MBID) (N = 117; M(IQ) = 71.34; SD(IQ) = 8.00, range: 52-85).

Methods: A full WAIS-III was administered as a standard procedure in the diagnostic process.

Results: The results indicate an excellent reliability (r = 0.96) and a strong, positive correlation with the full WAIS-III (r = 0.89). The SF correctly identified ID in general and the correct IQ category more specifically in the majority of cases (97.4% and 86.3% of cases, respectively). In addition, 82.1% of the full scale IQ (FSIQ) estimates fell within the 95% confidence interval of the original score.

Conclusions: We conclude that the SF is a reliable and valid measure to estimate FSIQ. It can be used in clinical and research settings when global estimates of intelligence are sufficient.