An examination of the equivalence of the first grade DIBELS oral reading fluency probes

Given the change in federal legislation allowing the consideration of a Response-To-Intervention (RTI) approach to making eligibility decisions for specific learning disabilities (IDEIA, 2004), it is crucial to establish sufficient evidence for using curriculum-based measurements (CBM) or CBM-like measures (e.g., Dynamic Indicators of Basic Early Literacy Skills; DIBELS) for monitoring students' responses to interventions as part of the identification process for Specific Learning Disabilities. One critical component in an effective RTI model is the availability of parallel measures suited for frequent progress monitoring to index student performance over time. The current study investigated the equivalence of the twenty first grade DIBELS Oral Reading Fluency (DORF) progress monitoring probes' using a one-way ANOVA for repeated-measures. Participants were 68 first grade students (36 females and 32 males) from two Midwestern elementary schools. No selection criteria other than parental consent were used. The DORF probes were given in a pseudo-counterbalanced order across four days at the end of the school year to avoid instruction and practice effects. The standard error of measurement (SEM) of the twenty first grade DORF progress monitoring probes was calculated using alternate form reliability coefficients. Results suggested that the equivalence assumption of the first grade DORF was not held. Most of the probes were significantly different in their difficulty level from each other and did not yield consistent mean levels of performance. The findings also suggested a significant magnitude of score fluctuation at the individual student level. The average SEM value was about 9 (ranging from 8 to 10), similar to previous research findings using test-retest reliability for calculation. Limitations, educational implications for CBM ORF users and researchers, and directions for future research are presented.