The correlation of both raw and scaled scores between different scales was low to moderate in all age groups (Spearman’s ρ mostly within the range of 0.3–0.6 p < 0.001 for all pairwise correlations). Results: The average scaled scores of the examined children were generally comparable with the original (US) Bayley-III norms, with the exception of those older than 1 year, who demonstrated 1.2–1.9 points better performance in cognitive development and gross motor skills and 0.9–2.6 points lower performance in expressive communication. Reliability and validity of the translated instrument were examined using correlation analysis, tests of internal consistency, and confirmatory factor analysis (CFA). The development scores of the sample children were compared with the original Bayley-III norms in each age strata separately.

For the purpose of psychometric analysis, we selected the data for four age groups of children from the longitudinal study database: 4–6 months ( N = 149), 10 months ( N = 138), 15 months ( N = 151), and 24 months ( N = 124). Within the project, the original Bayley-III manual was translated into Russian and then used in a cohort of 333 infants to assess cognition, expressive/receptive communication, and fine/gross motor skills. Materials and methods: This psychometric study was part of the longitudinal study conducted by the Ural Federal University in 2016–2020. No comprehensive psychometric studies of the Bayley-III have yet been performed in Russia. Introduction: The Bayley Scales of Infant and Toddler Development–third edition (Bayley-III) is one of the most widely used tools for assessing child development, and adapted versions of this instrument have been successfully used in many countries. 2Department of Preventive and Family Medicine, Ural State Medical University, Yekaterinburg, Russia.1Laboratory for Brain and Neurocognitive Development, Department of Psychology, Ural Institute of Humanities, Ural Federal University, Yekaterinburg, Russia.Polina Pavlova 1*, Dmitry Maksimov 1,2, Dmitry Chegodaev 1 and Sergey Kiselev 1

Bayley iii reliability and validity