Validity and reliability of grammar section of the MacArthur- Bates Communicative Development Inventories-Toddler form in 16-30 months old Persian-speaking children in Isfahan

Toddlers’ language abilities are difficult to assess using either standard tests or through language sampling. Parents’ report is a valid alternative way of assessment which is broadly applicable for clinical and research purposes. MacArthur-Bates Communicative Development Inventories (MCDI) is one of the most widespread questionnaires applying for this reason. The current study aims to investigate the content validity and reliability of the grammar section of MCDI-Toddler form in 16 to 30 months old Persian-speaking children in Isfahan.
Method and materials: After adapting the grammar section of MCDI-Toddler form into Persian, its content validity was essayed using content validity ratio (CVR). The inventory, then, were sent out to the parents of 50 typically developing children in order to determine the internal consistency of the form. The sample were randomly selected from 10 health centre in Isfahan city. Test-retest reliability was calculated for 20 children with a two-week’s time interval between test and retest phases. Cronbach’s alpha and Pearson correlation coefficient were used to determine internal consistency and test-retest reliability, respectively.
Calculated CVR was acceptable for more than half of the items. Consequently, those items with lower CVR were modified according to the experts’ opinions. All modified sub-sections but one showed high internal consistency (over 0.72) and high test-retest reliability (0.79 and over).
Grammar section of Persian MCDI-Toddler form is valid and reliable enough to be assayed in further phases of diagnostic studies including normalizing and diagnostic accuracy studies.