An examination of variability as a function of passage variance in CBM progress monitoring

This study examined the effects of controlling the level of difficulty on the sensitivity of repeated curriculum-based measurement (CBM). Participants included 99 students in Grades 2 through 5 who were administered CBM reading passage probes twice weekly over an 11-week period. Two sets of CBM reading progress monitoring materials were compared: (a) grade level material that was controlled for difficulty, and (b) uncontrolled randomly selected material from graded readers. Students' rate of progress in each progress monitoring series was summarized for slope, standard error of estimate, and standard error of slope. Results suggested that controlled reading passages significantly reduced measurement error as compared to uncontrolled reading passages, leading to increased sensitivity and reliability of measurement.