Differences in specific learning disability identification with the Woodcock-Johnson IV

Area of Science:

• Educational Psychology
• Neuropsychology
• Psychometrics

Background:

• The Ability Achievement Discrepancy (AAD) model is a primary method for identifying specific learning disabilities in schools.
• The Woodcock-Johnson IV (WJ-IV) offers two distinct scores for assessing ability: general intellectual ability (maintaining overlap with basic psychological processes) and fluid-crystallized intelligence (minimizing overlap).

Purpose of the Study:

• To examine how using different ability scores within the AAD model affects the identification of specific learning disabilities.
• To compare identification rates and characteristics of students identified using general intellectual ability versus fluid-crystallized intelligence scores on the WJ-IV.
• To investigate demographic differences, specifically racial representation, in identification outcomes.

Main Methods:

• Analysis of a standardization sample of 3,736 individuals from the WJ-IV.
• Utilized chi-square tests of independence and absolute ratios to compare identification proportions.
• Employed multivariate analysis of variance (MANOVA) and Tukey's HSD for academic achievement comparisons, and Mann-Whitney U tests for identifying contributing WJ-IV tests.

Main Results:

• Different proportions of individuals were identified based on the chosen ability score (general intellectual ability vs. fluid-crystallized intelligence), despite similar academic achievement scores.
• Black students were overrepresented, and White students were underrepresented in the identified groups compared to their proportions in the overall sample.
• Discrepancy profiles were more influenced by the internal psychometric properties of the WJ-IV subtests than by individual student characteristics.

Conclusions:

• The choice of ability score significantly impacts learning disability identification rates within the AAD model.
• The study highlights potential biases in identification, with demographic disparities noted, particularly concerning Black and White students.
• Findings suggest that the psychometric characteristics of assessment tools, like the WJ-IV, play a crucial role in identification outcomes, necessitating careful consideration in practice.