Doctoral Dissertations

Date of Award

8-2002

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Education

Major Professor

R. Steve McCallum

Committee Members

Sherry M. Bell, Donald J. Dickinson, Richard S. Saudargas

Abstract

The Test of Dyslexia and Dysgraphia (TODD) was designed to provide a comprehensive assessment of dyslexia in a theoretically based and timely manner. It is based on the work of Padget, Knight, and Sawyer (1996) and Wolf (1999) and includes measures of intelligence, academic achievement, and basic cognitive processes believed to be related to reading. The TODD was administered to 105 students ranging in age from 5 to 13 years old. These children were randomly selected from two schools in a school district in East Tennessee. Each child was administered the entire TODD battery. Measures of reliability and construct validity were obtained. Results suggest that the TODD has adequate reliability based on measures of internal consistency. Reliabilities ranged from .97 to .68 and are comparable to other similar assessment instruments. The first measure of construct validity was completed using age-to-raw score correlations. Correlations for each TODD subtest were significant at the .01 level and ranged from .38 to .80. Finally, exploratory factor analyses were conducted to determine the factor structure of the 8 subtests used to measure the basic cognitive processing variables. Data from the initial factor analysis and from the reliability analysis led to the decision to eliminate one subtest-Auditory Gestalt: Closure and to perform a 2 nd exploratory factor analysis. This 2nd factor analysis yielded Two and Three Factor Models that seemed consistent with current reading research. Factor One of the Two Factor Model, called Auditory Processing, included: Memory of Symbols (.81), Phonological Awareness (.80), Word Memory (.77), Auditory Gestalt: Synthesis (.71) and Rapid Symbol Naming (.65). Factor Two, called Visual Processing/Speed, contained Visual Processing: Closure (.94) and Visual Processing: Discrimination (.81). Visual Processing: Discrimination has a secondary loading of .46 on Factor One and Rapid Symbol Naming has a secondary loading of .59 on Factor Two. The Three Factor Model . showed similar loadings but resulted in a separate Memory Factor defined by loadings of the Word Memory (.90), Memory for Symbols (.50), and Rapid Symbol Naming (.47) subtests on a 3 rd factor. Results of this study suggest that the TODD shows promise for providing professionals with a tool that will enhance the assessment and diagnosis of dyslexia.

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