Date of Award

Spring 5-10-2014

Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Rose A. Sevcik

Second Advisor

Robin D. Morris

Third Advisor

Lee Branum-Martin

Fourth Advisor

Paul T. Cirino


Children with mild disabilities are known to have difficulties with developing mathematical skills (Hoard, Geary, & Hamson, 1999). Yet, children with mild intellectual disabilities (MIDs) have rarely been included in rigorous scientific research. The present study has three goals. The first goal was to determine the structure of mathematics achievement in elementary aged children with MIDs and children with reading disabilities (RDs) without accompanying mathematics disabilities. The second goal was to establish the measurement stability of mathematics achievement. The third goal was to evaluate students’ response to a mathematics intervention. The participants were 265 children with MIDs and 137 children with RDs. Confirmatory factor analysis and measurement invariance evaluation was utilized to determine the structure of mathematics achievement and to ensure reliable and valid measurement of mathematics achievement between groups across three time points. The results of measurement invariance evaluation indicated that a joint model specification, characterized by two groups, both of which included children with MIDs and children with RDs who were differentiated according to intervention condition participation (not disability status), provided the best account of the underlying data structure. Further, the structure of mathematics achievement in the present sample was unidimensional, and the measurement of mathematics achievement was temporally stable between groups. Finally, latent mathematics achievement growth was evaluated. The results indicated that students in the mathematics intervention condition evidenced an advantage over those in a reading intervention condition at mid- and post-intervention evaluation, while also evidencing more growth in this conceptual domain. Instructional implications are discussed in terms of topic choice and pacing.