Psychometric properties of the MacArthur-Bates communicative development inventories – III (CDI-III) in 30 to 37 months old Persian-speaking children

Introduction: Early language skills predict the child’s future language skills and literacy. So, screening and assessment of speech and language at an early age is important. One of the cost-effective way of child’s communication assessment is through parents reporting tools. MacArthur-Bates Communicative Development Inventories (CDI) are the most widely used forms that have been appliedby professionals in more than 70 live languages around the world to screen children’s communication skills. The main purpose of this study was to providethe Persian edition of the third form of CDI (CDI-III) and determining its psychometric properties including face and content validity and internal consistency in 30 to 37 months old Iranian Persian-speaking children. Method and Materials:In a cross-sectional methodological study of instrument validation, a Persian adapted form of CDI-III was developed. At first the English form adapted to Persian and a Delphi method was used to provide the initial list of the items. The face and content validity were examined by asking the opinion often Persina-speaking speech and language pathologists with at least three years of clinical experiencein the field of child speech/language development and disorders. The final form was compiled based on the results of the content validity ratio (CVR) and content validity index (CVI) of the items. The final form consisted of three sections including vocabulary, sentences, and use of sentences. The parents of 356 Persian-speaking children aged 30 to 37 months who were recruited by multi-stage cluster random sampling from health centers in Isfahan city were asked to complete the form. Internal consistency was assessed by Kuder-Richardson coefficient and correlation was examined by Spearman coefficient. Results: The items with CVIs greater than or equal to 0.7 and CVRs greater than or equal to 0.6 remained, and other items were reviewed or removed based on the suggestions of panelists and developers. The final form included 100 words, 22 pairs of sentences and 16 questions about use of sentences. A total of 356 children (mean age = 34.03 months ± 2.12 standard deviation) were included in the study. According to the English CDI-III guidelines, the data were divided into four age groups with two-months intervals, i.e. 31-30, 33-32, 35-34, and 37-36. The internal consistency of the whole form was 0/97 and internal consistency of vocabulary, sentences, and sentence usage were calculated as 0/98, 0/88, and 0/88 respectively. Spearman correlation values between the scores of the form sections together and each section with age indicated that there was a positive significant correlation between allsections of the form. Also, the positive significant correlation between age and all three parts showed that the number of expressive words, the grammatical complexity of sentences, and the proper use of sentences increase with age. Conclusion:The Persian CDI-III form possesses good face and content validity and internal consistency to be used as a valid tool for screening  language competence of 30-37 month old Persian-speaking children. The results of mean and standard deviation of the current study can be used as a comparison for screening children who are suspected of being language deficient.