The predictive validity of Bayley Scales of Infant and Toddler Development-III at 2 years for later general abilities: Findings from a rural, disadvantaged cohort in Pakistan

Using data from a rural cohort in Pakistan (N = 1298), the study examined the predictive validity of the Bayley Scales of Infant and Toddler Development (BSID) 3^rd edition on later tests of general abilities. The BSID III subscales (cognitive, language and motor) were administered at 2 years; general ability was assessed using the Verbal, Performance and Full-Scale score from the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) III at 4 years, and the Fluid Reasoning Index (FRI) from the Wechsler Intelligence Scale for Children (WISC) V at 8 years. The combined BSID subscales explained 15% of the variation of the WPPSI III full scale, 16% of the Verbal scale, 7% of the Performance scale and 1% of the FRI. BSID III scores at 24 months should be used with caution to predict future intellectual abilities.