ABSTRACT

Objective: This study verified the psychometric properties of gross motor scale of Korean version of Bayley Scales of Infant and Toddler Development-Third Edition(K-Bayley-Ⅲ) through item analyses, validity, and reliability evidence. Methods: Date were obtained from a stratified sample of 1,764 infants and toddlers divided into 17 age groups, 16 days through 42 months 15days old, who reflected key demographic variables in the national population. Results: Firstly, the analysis of the degree of item difficulty indicated that items were appropriately placed in the order of difficulty. Most baseline items showed a 90% pass rate. Secondly, Inter-item consistency showed excellent levels and items were highly reliable in terms of test-retest reliability and inter-rater reliability. Thirdly, in terms of the construct validity, the Gross Motor Scale of K-Bayley-Ⅲ score revealed a high degree of correlation with the Motor composite score but a significant moderate correlation with the Language composite score, providing evidence of its convergent and discriminant validity. Conclusion: In this study, K-Bayley-Ⅲ gross motor scale was proved to be a valid and reliable measure for evaluating the development of gross motor in Korean infants.