Q & A with John Kranzler, Ph.D., Professor in the School of Special Education, School Psychology, and Early Childhood Studies

What basic questions does your research seek to answer?

My recent empirical research has largely fallen within the evidence-based practice (EBP) movement within the field of school psychology, which aims to “identify, disseminate, and promote the adoption of practices with demonstrated research support” (Kratochwill, 2007, p. 829). The goal of the EBP movement is to improve the quality of professional services (e.g., diagnosis, intervention, and evaluation) delivered to children and youth, families, and schools. Of particular interest to me at the current time is the innovative approach to the identification of specific learning disabilities (SLD) known as the pattern of strengths and weaknesses (PSW) approach. PSW methods define SLD as unexpected underachievement and corresponding weakness in specific cognitive abilities. The PSW approach has already been adopted in 14 states for SLD identification (Maki, Floyd, & Roberson, 2015), despite the fact that substantiating scientific evidence is currently lacking. Thus, I have conducted several investigations of important postulates underlying the PSW approach. Below I describe two recent studies my colleagues and I have conducted to provide some description of my work.

One postulate of the PSW approach concerns the focus of IQ test interpretation. Proponents of the PSW approach contend that the focus of interpretation should not be on the overall score, but on the pattern of intra-individual strengths and weaknesses at the composite score level. For composite scores to warrant interpretation, they must demonstrate incremental validity. Incremental validity addresses the question of whether scores on a test increase the predictive validity of important external criteria over other scores on the same test or scores on other established measures. To examine this question, my colleagues and I used estimated factor scores from a bifactor analysis of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) to examine the unique effects of its latent variables on academic achievement. Results of this study only partially replicated the findings of previous research on the incremental validity of scores that can be derived from performance on the WAIS-IV. Although we found that psychometric g is the most important underlying construct measured by the WAIS-IV for the prediction of academic achievement in general, results indicated that only the unique effect of Verbal Comprehension was important, and only for certain academic outcomes. Results of this study, which was published in Psychological Assessment (Kranzler, Floyd, & Benson, 2015), question the utility of composite scores underlying the PSW approach.

Valid identification of SLD using the PSW methods requires the application of diagnostic criteria that result in the reliable grouping of children and adolescents with this disability and those who do not. We examined the diagnostic accuracy of the Cross-Battery Assessment (XBA) PSW approach to identifying SLD. To examine this postulate, we conducted a classification agreement analysis using the Woodcock-Johnson III Tests of Cognitive Abilities and Achievement. We examined the broad cognitive abilities of the Cattell-Horn-Carroll theory held to be meaningfully related to basic reading, reading comprehension, mathematics calculation, and mathematics reasoning across age. Results of analyses of 300 participants in three age groups (6-8, 9-13, and 14-19 years) indicated that the XBA method is very reliable and accurate in detecting true negatives. Results of classification agreement analyses were generally quite low, however, indicating that this method is very poor at detecting true positives. Mean sensitivity and positive predictive value were 21% and 34% across all broad cognitive abilities and academic domains. In sum, results of this study do not support the use of the XBA method for identifying SLD. Results of this study, as well as a reply to commentary on our article by PSW proponents, are in press in the International Journal of School Educational Psychology.

What makes your work interesting?

My primary area of scholarly interest concerns the nature, development, and assessment of intelligence (IQ). Standardized IQ tests have been called psychology’s greatest contribution to society. The overall score on these tests is a better predictor of achievement in school or college, military training programs, and employment in business and industry than any other combination of variables independent of IQ. The interpretation and use of IQ tests, has long been surrounded by controversy, however. Indeed, IQ tests have been used to admit, advance, and employ, but also to deny, track, and institutionalize. Much of my work in recent years has concerned investigating the validity of innovative practices involving the interpretation and use of the results of IQ tests.

What are you currently working on?

My future research agenda involves extension of research on the PSW methods, SLD identification, and valid interpretation of IQ tests. I recently received IRB approval for a study on the cognitive ability profiles of children and youth identified as SLD in a response-to-intervention model. In addition to empirical research, I recently co-authored a textbook on intellectual assessment titled, Assessing Intelligence in Children and Adolescents: A Practical Guide. Our aim in writing this book was to address the need for an updated, evidence-based, user-friendly resource to meet the training needs of students and practitioners. I also guest edited a special issue of the International Journal of School & Educational Psychology on current practices and future trends in the intellectual assessment of children and youth around the world, which will be published this fall.