Floor effects associated with universal screening and their impact on early identification of reading disabilities

摘要

Response to intervention (RTI) holds great promise for the early identification and prevention of reading disabilities. The success of RTI rests in part on the accuracy of universal screening tools used within this framework. Despite advancements, screening instruments designed to identify children at risk for reading disabilities continue to have limited predictive validity. In this study, we examine a common screening instrument for the presence of floor effects and investigate the impact that these effects have on the predictive validity of the instrument. Longitudinal data (kindergarten-3^rd grade) from a large cohort of children were used. These data included children’s performances on five measures from DIBELS (Dynamic Indicators of Basic Early Literacy Skills) and two reading achievement outcome measures. Results showed that DIBELS measures were characterized by floor effects in their initial administrations, and that these effects reduced the predictive validity of the measures. The implications of these findings for early identification are discussed.