Relative Proficiency Index
The Relataive Proficiency Index (RPI) predicts a student's level of proficiency on tasks that typical age- or grade-peers would perform with 90% proficiency. For example, an RPI of 55/90 on the Letter-Word Identification subtest would indicate that on similar tasks, the student would demonstrate 55% profiencieny, whereas age- or grade-peers would demonstrate 90% accuracy.
The RPI can document a performance deficit that may not be apparent based on the peer comparison (standard score, percentile rank).
The RPI score may be compared to a score on an Informal Reading Inventory for interpretive purposes. Paralleling IRI criteria are as follows: