Student growth percentiles allow us to look at student performance over time, relative to peers. SGP's are a number ranging from 1 through 99, with the higher the number meaning better performance. NJDOE recommends that student growth should be between the 35th and the 65th percentile, for average growth. Student growth percentile is calculated by comparing a student’s achievement that of his academic peers. Furthermore, academic peers are students throughout the state with similar test score histories. For instance, in the state of New Jersey students with similar NJASK test score histories are considered academic peers. Student growth percentiles do not take into account for any demographic factors such as gender or ethnicity, or specific programs such as English language learners or students with disabilities when identifying academic peers. However, academic peers are in the same grade, took the same tests (such as the NJASK), and have achieved similar results on past tests.
Furthermore, student growth percentiles look at how similar students change to find what typical growth is for a group of students. It allows us to find students who are making fast/more progress and students who are making slower/less progress. From there, it also allows us to investigate what is and isn’t working for students.
Over the years states may change their tests, resulting in the question, “Can we still compare test scores across years if the tests change?” The answer is yes. Luckily, student growth percentiles do not require identical tests or scales every year. This is because they measure normative growth, meaning that students are being compared tot heir academic peers taking the same assessment making the calculation reliable.
It has been proposed by NJ Department of Education officials that the New Jersey Student Growth Percentile measures to be used for evaluating teachers and principals and rating local public schools. The NJDOE proposed tat NJ student growth percentiles be used as a major component for determining teacher effectiveness as well, having consequences for employment if rating are low. It has been revealed that Student Growth Percentiles are “not designed for inferring teacher influence on student outcomes,” they “do not control for various factors outside of the teacher’s control,” they’re “not backed by research on estimating teacher effectiveness. By contrast, research on SGPs has shown them to be poor at isolating teacher influence,” and NJ SGP measures, “at the school level, are significantly statistically biased with respect to student population characteristics and average performance level.”
“Using Student Growth Percentiles,” NJ Smart Education Data System. http://survey.pcgus.com/njgrowth/player.html
State of Washington OSPI. http://www.k12.wa.us/assessment/SGP/FAQ.aspx#1
Deconstructing Disinformation on Student Growth Percentiles & Teacher Evaluation in New Jersey. Student Finance 101. http://schoolfinance101.wordpress.com/2013/05/02/deconstructing-disinformation-on-student-growth-percentiles-teacher-evaluation-in-new-jersey/