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This page provides Washington school district and ESD personnel with an
overview of student growth percentiles, a new method of measuring student
academic growth introduced by OSPI in March 2013.
This page will answer the following questions:
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, information can be shared in percentile terms that are familiar to most teachers and parents.
Washington’s state assessments are not vertically scaled. This means the different MSP grade level tests do not combine to form one long yardstick for measuring growth in math or reading from one grade level to the next. Therefore we cannot measure a student’s absolute growth by comparing last year’s scale score to this year’s. Instead, we can measure student growth by calculating student growth percentiles that indicate the amount of growth a student made in a testing subject over the course of one year, relative to their academic 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.
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:
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. A student’s growth percentile represents how much a student grew in comparison to these academic peers.
The median growth percentile summarizes student growth rates 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.)
Yes, because we are measuring normative growth, (i.e. students are being compared to their academic peers taking the same assessments), it is possible to calculate growth reliably. Student Growth percentiles do not require identical tests or scales from year to year.
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. 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.
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 between the school years 2005-06 and 2011-12.
All students in the state that have valid and consecutive test scores are included in the comparison group, forming the norming population for the calculation of the SGPs. Each year that student growth is calculated, the norming population will consist of students enrolled and tested in that subject during that school year.
If students tested in the grades listed below, in addition to testing in at least one year prior, they will receive a growth percentile.
| Grade Tested |
Math |
Reading |
| 4th Grade |
MSP |
MSP |
| 5th Grade |
MSP |
MSP |
| 6th Grade |
MSP |
MSP |
| 7th Grade |
MSP |
MSP |
| 8th Grade |
MSP |
MSP |
| 9th Grade |
EOC Math 1 |
NA |
| 10th Grade |
EOC Math 1 |
HSPE |
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 be provided for the school years 2010-11 and 2011-12.
Student growth for end-of-course exams will be calculated for EOC Math 1 - Algebra, using the student’s prior 8th grade MSP math score. If a student took and tested in Algebra 1 in 8th grade or lower, OSPI is only providing their MSP scores at this time. Additionally, SGPs will not be produced for Science, Writing, EOC Geometry or EOC Biology.
Students that are included in district aggregations are those that have been continuously enrolled in the district in the school year tested. Additional aggregation rules will be made available to districts with their data.
Growth percentiles have been calculated for subjects in 10th grade even though those students would not have had a prior year score. SGPs for students who test in 10th grade are less straightforward, because of the 9th grade test gap and thus one must use caution when interpreting those scores. One needs to say “how has this student done over the past TWO years, relative to academic peers using 8th grade and prior scores”. Attributing 10th grade SGPs to a teacher is not recommended, but the information is useful in evaluating a student’s progress toward proficiency.
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 Reading, 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?
OSPI will release the student growth percentile data in March 2013. Student growth percentiles will be calculated and provided for the school years of 2010-11 and 2011-12. The following documents will be made available to districts:
- Individual student reports, including one student growth chart for each subject
- School-level reports that show individual students’ growth percentiles; one report for each subject/grade combination
- District-level reports that show the median growth percentile of each school
- Flat data files that include SGPs at the student level and aggregate data at the school, district, and student group levels
Download examples of these reports.
School Districts Currently, student growth and median growth percentiles are being provided to school districts to become familiar with the concept and methodologies and to use at their discretion. The flat data files available to districts can be aggregated in multiple ways that can demonstrate powerful trends. In fall 2013, when data from spring 2013 assessments are published, OSPI recommends that districts make the student reports available to families.
The State Board of Education’s Accountability Index SGPs will also be incorporated into Washington’s federal accountability measures. In the future, the student growth percentiles will be incorporated into the revised State Board of Education’s Accountability Index. This release of the revised index is anticipated for September 2013 and will refer/apply to the 2012-13 school year. At that time, OSPI may also provide “adequate growth” data. Adequate growth is the approximate student growth percentile that would be necessary for the student to reach their fixed achievement targets (e.g., proficiency) within 4 years or 10th grade, whichever comes first. Adequate growth will be aggregated at the school and district level and may be used in the Accountability Index.
Teacher Principal Evaluation Project (TPEP) Districts may
eventually choose to use student growth percentiles as a component in teacher
evaluation. SGPs could inform teacher evaluations if schools attribute
individual students to specific teachers. OSPI advises against using student
growth data for evaluation of performance during the 2013-14 school year and
recommends waiting until the 2014–15 school year. For more details on the use of student growth percentiles in teacher evaluation, please see the TPEP Statement on Student Growth Percentiles. More information on this topic
will be available by visiting the
TPEP Web site.
Districts will receive electronic versions of select reports. These reports and
the flat file(s) will be available to districts in the Washington Assessment
Management System (WAMS) accessed through the EDS portal.
OSPI will report student subgroup, school and district-level median student growth percentiles publicly in fall 2013 on the OSPI Report Card (or other) website and will make available an interactive website which will have visualization tools for the SGP data.
Background on Student Growth Percentiles:
OSPI Webinar: Introduction to SGP (36-minute video)
The Colorado Growth Model – SchoolVIEW. Colorado Department of Education.
The DC Schoolwide Growth Model – Frequently Asked Questions. DC Public Charter School Board.
Growth: Measuring Idaho’s Students. Idaho Department of Education.
Student Growth Percentiles. Seattle Public Schools (PG & E Video Series).
Please note: Seattle Public Schools controls for additional student characteristics in their model, whereas the model used by OSPI only controls for students score history.
Articles Cited:
Betebenner, D. 2011.
A Technical Overview of the Student Growth Percentile Methodology: Student Growth Percentiles and Percentile Growth Projections/Trajectories. The National Center for the Improvement of Educational Assessment.
Cade, B and Noon, B. 2003.
A gentle introduction to quantile regression for ecologists. Frontiers in Ecology and the Environment. 1(8): 412 – 420.
Koenker, R and Hallock, K. 2001. Quantile Regression. Journal of Economic Perspectives. 15(4): 143-156.
Yen, W. M. 2007. Vertical scaling and No Child Left Behind. In N. J. Dorans, M. Pommerich,
& P. W. Holland (Eds.), Linking and aligning scores and scales (pp. 273{283). New York: Springer.
OSPI is very interested in hearing your questions, recognizing student growth percentiles are a new and complex method of assessing student growth. We look forward to continued communication. Please email your questions and feedback to studentgrowth@k12.wa.us
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