The Misconception of the Regression-Based Discrepancy Operationalization in the Definition and Research of Learning Disabilities

Abstract

In this article, I argue that the regression-based discrepancy method used in the diagnosis of learning disabilities is invalid because it is inconsistent with the underlying underachievement concept of which it is intended to be the operationalization. I mathematically demonstrate that the regression-based discrepancy method largely reflects achievement-specific determinants, thereby defeating its own object of describing aptitude-achievement discrepancies. The implications for research examining the role of intelligence in learning disabilities are outlined.

Differential Genetic Etiology of Reading Difficulties as a Function of IQ: An Update

“…Although some reference to cognitive/intellectual ability has historically been included in most definitions of dyslexia, either in the form of discrepancy scores (e.g., Critchley, 1970; Rutter & Yule, 1975) or IQ cut-off (e.g., Siegel, 1989), the past two decades have brought increasing criticism of these models (e.g., Gustafson & Samuelsson, 1999; Lyon, 1989,1995; Siegel,1998, 2006; Stanovich & Siegel, 1994; Van den Broeck, 2002) and a tendency toward exclusion of IQ from the definition of RD (e.g., Aaron et al, 2008; Siegel, 2006). However, even the most recent working definition of dyslexia (Lyon et al, 2003) adopted by the International Dyslexia Association and the National Institute on Child Health and Human Development includes the phrase “…is often unexpected in relation to other cognitive abilities…” Although the use of discrepancy scores or an IQ cutoff is intended to ensure that learning difficulties are not due to general cognitive deficits (Lyon, 1996; Stanovich, 1986), this “assumption of specificity” (Stanovich, 1986) implies that specific reading disability is etiologically distinct from reading deficits associated with more general learning difficulties (Olson et al, 1991; Lyon et al, 2003).…”

Misconceptions Regarding Accommodations on High‐Stakes Tests: Recommendations for Preparing Disability Documentation for Test Takers with Learning Disabilities

“…Courts tend to place more weight on the clinical judgment of expert testimony rather than deferring to a cutoff score (Simon, 2007). Research on discrepancy models show problems with discriminant validity within these models (Van den Broeck, 2002a; Proctor & Prevatt, 2003) and point to “limited reliability because of their reliance on a measurement at a single time point” (Fletcher, Denton, & Francis, 2005, p. 545). An inherent problem with the intra‐individual discrepancy model is the assumption that cognitive weaknesses automatically lead to selected and narrow difficulties in achievement, which can be improved upon by accommodations alone .…”

Complete Issue (Merle Richards, editor)

“…Malgré le fait que de nombreuses méthodes de dépistage soient utilisées de nos jours, entre la première et la troisième année, il n'existe pas encore de tests uniformes permettant de dégager un portrait représentatif des difficultés d'apprentissage rencontrées chez les élèves du primaire (Scruggs et Mastropieri, 2002). Ces méthodes s'appuient sur de nombreuses conceptions du dépistage (Van den Broeck, 2002). Ces méthodes portent encore largement sur la mesure des capacités intellectuelles de l'enfant (Fletcher et al, 1998;Van Noord et Prevatt, 2002), sur son développement (Klee et al, 2000;Mardell-Czudnowski et Goldenberg, 1998), sur sa réussite ou son aptitude scolaire (Deslandes et al, 1998) et, plus récemment, sur un grand nombre de variables indépendantes qui tentent d'identifier les enfants les plus à risque (Goldstein et Taylor, 1998), telles que l'indice de préférence sociale des pairs et l'aspect social du comportement (Cobb et al, 1998), les attitudes, l'implication et la participation parentales (Prêteur et al, 1998;Salomon et Comeau, 1998).…”