Purpose: To determine concurrent validity of the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) and the Peabody Developmental Motor Scales, Second Edition (PDMS-2).
Method: Tests were administered to 48 children with corrected age ranging from 29 days to 26 months. Concurrent validity between age-equivalent (AE) scores and standard scores was assessed for 4 age groups.
Results: Moderate to very high correlation for all groups was found between the Bayley-III composite scores and the PDMS-2 Total Motor quotient scores. High correlations were found between the Bayley-III composite scores and the PDMS-2 Gross and Fine Motor quotients (12–26 months); high correlations were found between the Bayley-III and the PDMS-2 Gross Motor quotient (6–12 months) and moderate correlations were found for younger age groups. High concurrent validity for AE scores was found only above 18 months.
Conclusions: The study supports the substitution of the Bayley-III for the PDMS-2 for standard scores or AE scores for children aged 19 to 26 months and for standard scores for children birth to 18 months.