a psychometric study of the bayley scales of infant and toddler development test in persian language children

objectives : bayley scales of infant & toddler development is a well-known diagnostic developmental assessment tool for children aged 1–42 months. our aim was investigating validity & reliability of this scale in persian speaking children. materials & methods: the method was descriptive-analytic. translation- back translation and cultural adaptation was done. content & face validity of tranlated scale was determined by experts’ opinions. 403 children aged 1 to 42 months were recruited from health centers for developmental assessment in cognitive, communicative (receptive & expressive) and motor (fine & gross) domains. reliability of scale was calculated through three methods; internal consistency using cronbach's alpha coefficient, test-retest and interrater methods. construct validity was calculated using factor analysis and comparison of the mean scores methods. results: cultural and linguistic changes were made in items of all domains especially on communication subscale. content and face validity of the test were approved by experts’ opinions. cranach’s alpha coefficient was above 0.74 in all domains. pearson correlation coefficient in various domains, were ≥ 0.982 (p< 0.01) in test retest method, and ≥0.993 (p<0.01) in inter-rater method. construct validity of the test was approved by factor analysis. also, the mean scores for the different age groups were compared and statistically significant differences were observed between mean scores of different age groups, that confirms validity of the test. conclusion : the bayley scales of infant and toddler development is a valid and reliable tool for child developmental assessment.