Percent Accuracy for the Star CBM Passage Oral Reading Measure

For Star CBM Passage Oral Reading assessments, you'll see a Percent Accuracy score in addition to the Correct Per Minute (CPM) score. (Benchmarks for Passage Oral Reading Assessments are based on students' CPM scores.)

There are multiple Passage Oral Reading forms at each grade level. To make the results from all forms comparable, and to provide a basis for calculating the norm-referenced scores, Star CBM converts (or equates) the percent accuracy scores to a common form. Equating eliminates differences in form difficulty so that scores can be interpreted on the same scale. Star CBM does this in three steps:

1. Star CBM records the number of words read correctly on a form (Correct Count) and the number of words attempted (Attempted Count).
2. The Correct Count and Attempted Count score on all of the other forms is equated to the form that has been identified as the easiest form.
3. Star CBM converts the equated correct count to a percent accuracy score. To do this, it divides the equated correct count by the equated number of items attempted. The result is multiplied by 100, then rounded to a whole number.

As a result, percent accuracy scores indicate the same level of performance across forms, and they can be interpreted regardless of the specific form taken in a measure.