Interpretation, Reporting, and Visualization of Student Growth Percentiles

Because Student Growth Percentiles (SGP) is a relatively new evaluation method, appropriate interpretation and reporting is extremely important. As it is often defined, SGP is a relative measure of a student’s growth/change compared with his or her academic peers. Prior to interpretation, “academic peers” must be clearly defined. In academic subject areas, students in the same grade in a defined unit (e.g., state, school district, or school), who received similar scores on a standardized test at a previous testing time, are typically defined as the academic peers. For physical performance tests, however, age and gender may have to be included in the definition since both variables may have a direct impact on students’ performance. Both raw/scale scores and corresponding SGP should be reported and interpreted separately, comparing the former to criterion evaluation standards and the latter to the rate of change. Visualization of this information is often very helpful for interpretation.  Betebenner (2009) demonstrated some informative illustrations including a growth and achievement chart that is similar to the CDC growth charts and a SGP report card, where proficiency levels (unsatisfactory, partially proficient, proficient, & advanced) are summarized on the left vertical axis, growth level (low, typical, & high) on the right vertical axis and the student’s scale score and growth percentiles on the horizontal axis. Many other related reports and illustrations have been developed for school, district, and regional levels  and they will be presented along with related software and interpretations.