Using differential item functioning to validate a judgement-based assessment of emergent literacy for students with autism spectrum disorder

The co-occurrence of autism spectrum disorder with other disabilities blurs boundaries between patterns of learning related to, or impacted by, this disorder, and those related to other developmental or intellectual disabilities. This study extended previous research that suggested emergent skills among children with autism spectrum disorder could be fairly and meaningfully assessed using the same judgement-based protocols as for children with other learning disabilities (Woods, The design and validation of measures of communication and literacy to support the instruction of students with learning disabilities. Unpublished doctoral thesis, The University of Melbourne, Australia, 2010). One aim of the current research was to further investigate the validity of these assessment protocols, but with a larger group of students (n = 7967, 3145 of whom had a diagnosis of autism spectrum disorder) and with emphasis on learning in the early school years. A corollary aim was to use differential item functioning (DIF) analyses within a partial credit item response modelling approach to examine patterns of relative strength, challenge, and progress in literacy skills for children with autism. The outcome of the research builds knowledge of the assessment of literacy in young children with autism spectrum disorder. This is expected to help schools and teachers monitor and teach these foundational skills for children with both autism spectrum disorder and broader learning difficulties.