Student Growth Percentiles FAQ

A student growth percentile (SGP) describes a student's growth compared to other students with similar prior test scores (their academic peers). Although the calculations for SGPs are complex, percentiles are a familiar method of measuring students in comparison to their peers.

The student growth percentile allows us to fairly compare students who enter school at different levels. It also demonstrates a student's growth and academic progress, even if she is not yet meeting standard.

A student growth percentile is a number between 1 and 99. If a student has an SGP of 85, we can say that she showed more growth than 85 percent of her academic peers. A student with a low score on a state assessment can show high growth and a student with a high score can demonstrate low growth. Similarly, two students with very different scale scores can have the same SGP.

Frequently Asked Questions


How are student growth percentiles calculated?

Student growth percentiles are measured by using a statistical method called quantile regression that describes the relationship between students' previous scores and their current year's scores. For more discussion of the SGP model, please see the technical resources on the Student Growth School and District Resources webpage.

To whom are students being compared? What is an academic peer?

For SGPs, a student is compared to his/her academic peers. A student's "academic peers" are all students in Washington State in the same grade and assessment subject that had statistically similar scores in previous years. In other words, they are students that have followed a similar assessment score path. Students are only compared to others based on their score history, not on any other characteristics, such as demographics or program participation. A student's growth percentile represents how much a student grew in comparison to these academic peers.

What is a median growth percentile?

The median growth percentile summarizes student growth percentiles by district, school, grade level, or other group of interest. The median is calculated by ordering individual student growth percentiles from lowest to highest, and identifying the middle score, which is the median. The median may not be as familiar to people as the average, but it is similar in interpretation - it summarizes the group in a single number that is fairly calculated to reflect the group as a whole. (Medians are more appropriate to use than averages when summarizing a collection of percentile scores.)

At the state level, median SGPs are almost always 50 since norms are usually established using student scores from only the current year. Half of the state's students have growth below 50 and half above. In certain instances, statewide median SGPs may differ from 50 due to slight misfit, the assignment of Highest Obtainable Scale Score (HOSS) students to an SGP of 99, or the use of baseline method for calculating SGPs.

Can high scoring students still demonstrate growth?

Yes. Students that typically have high scores on state assessments will be compared to all other students in the state that also have high scores. If a student receives the Highest Obtainable Scale Score (HOSS), the student will receive an SGP of 99 in that year. The data show that even students that score at the top of the scale will have varied performance the next year, so the model allows us to identify growth for students at the upper end of the scale.

Which students get growth percentiles?

The students included in the student growth percentile calculations are those that attend public school and took a state assessment during the spring administration. Certain test types and categories of students are excluded from this comparison group. Only students that have at least two years of consecutive scores are included. For example, if a student has a score in 5th grade, but not in 6th grade, she would not be included in the analysis.

All available scores are used in the model, as long as they are consecutive. Washington's student growth percentiles are calculated using assessment data beginning in 2005-06. All students in the state that have valid and consecutive test scores in the same subject and grade form the norming population for the calculation of the SGPs.

Grade Tested Math ELA
4th Grade SBA SBA

Although the table lists the testing grade of students that would receive a student growth percentile, these students are now most likely in the next higher grade. SGPs will not be calculated for Science, Writing, EOC Biology, or EOC Math.

What can student growth percentiles tell us?

Student growth percentiles are primarily a descriptive model, telling us what amount of growth a student has made over the last year. This growth model is not a value-added model; it does not attempt to separate a teacher or school effect on student learning. SGPs can, however, help answer the following questions (Yen, 2007):

Parent Questions:

  • Is my child growing adequately toward meeting state standards?
  • Is my child growing more or less in Math than ELA, relative to other students in the state that scored similarly?

Teacher Questions:

  • Did my students grow adequately toward meeting state standards?
  • How much growth do my students need to become proficient?
  • Are there students with unusually low growth who need special attention?

Administrator Questions:

  • Are our students growing adequately toward meeting state standards?
  • How does the growth of students in my school compare to students in other schools?
  • Are students in different grade levels within my school growing similarly?
What kind of data will districts receive and when?

Districts will receive electronic versions of the following SGP reports beginning in late August to early September:

  • Individual student reports, including student growth percentiles charts for math and reading
  • School growth summary reports
  • Excel data files that include SGPs at the student-level and aggregate data at the school, district, and student group levels
  • These reports and excel files will be available to districts in the Washington Assessment Management System (WAMS) accessed through the EDS portal. District assessment coordinators can download the data by clicking on 'Profile', then 'File Downloads'.
Are Washington school districts required to distribute student growth reports to students and families?

It is at the discretion of Washington school districts whether or not to distribute student growth reports to families and students. OSPI recognizes that the model is complex, and, given other competing initiatives, investing the necessary time and energy into training on SGPs may be a lower priority.

Where did student growth percentiles originate?

Washington State student growth percentiles were developed by Damian Betebenner of the Center for Assessment (NCIEA). They were first developed in Colorado for use in their Accountability framework in 2007.

Where can I get more information?

Please visit the Student Growth District and School Resources webpage for additional videos and materials.

Recognizing that student growth percentiles are a complex method of assessing student growth percentiles, OSPI is very interested in hearing your questions. We look forward to continued communication. Please email your questions and feedback to Student Information.