Controlling IQ differences between reading disabled and normal children: an empirical example.

Abstract

Learning disability research has been the subject of much controversy in recent years. The research concern addressed in this paper relates to the equivalence of selected samples of learning disabled and normal children on measures of intelligence. LD and normal children often differ on measures of intelligence, as normal children score higher; intelligence test scores also are not similarly correlated with achievement measures for LD and normal children. This difference often is controlled in research investigations using analysis of covariance. When this procedure is used with LD children, assumptions underlying analysis of covariance frequently are violated. To illustrate this point, an empirical example is reviewed, with an interpretation of results when using analysis of covariance and an alternative procedure. Although specific procedures may be used with given samples of LD children to control for the IQ score difference, more research is needed to further clarify the nature of this difference.