Interpreting Student Growth Percentiles
Student growth percentiles (SGP) provide a more detailed picture of a student’s progress than traditional assessment reports, showing the relative achievement of each student to their academic peers. The SGP data allows educators to identify students who are making strong academic gains and those who need additional support.
SGPs are calculated using a statistical model called quantile regression. This model is designed to determine how a student’s current MCAS score compares with their previous scores and how much growth they have experienced. The technical resources on the Student Growth District and School Resources webpage provide further information about how SGPs are derived and their interpretation.
Students who receive a SGP are considered “proficient” or higher on the state’s proficiency scale. Educators can use SGP data to determine how well their students are progressing in the classroom and the content areas they are studying. Teachers who are not “proficient” can also make changes in their instruction to improve student performance.
When interpreting a student’s SGP, it is important to remember that the ranking of the student within the academic peer group is determined by their performance during the test administration. A student’s SGP does not depend on the rank of the other students in the academic peer group, but only on how much they grew or improved in their abilities during the test administration.
This means that two students with different MCAS scaled score histories could have the same SGP, but have very different relative performances in their academic peer groups. In other words, a student’s SGP tells us that they scored as high or higher than the majority of their academic peers in one of the previous MCAS tests.
A student’s SGP ranking in their academic peer group may change from year to year, but differences should be interpreted with caution. A change of less than 10 points should not be considered significant and may not reflect real differences in a student’s learning.
The NJDOE provides a variety of SGP data sets to assist districts, schools, and educators with their SGP analyses. The sgpdata package contains 4 examplar data sets that can be used for SGP calculations. One, sgpData, specifies data in the WIDE format that is utilized by the lower level SGP functions like studentGrowthPercentiles and studentGrowthProjections. The other two, sgptData_LONG and sgptData_INSTRUCTORNUM, contain teacher-student lookup tables that are utilized by higher level functions such as abcSGP and prepareSGP.
Districts submit course roster submission data to the NJDOE through SMART each summer for the upcoming school year. This data includes the course codes for the courses that each teacher teaches. The NJDOE then links this data to the relevant SGP data sets. The results of this process are then available to the district and educators for their use in SGP analysis and preparation. The sgpdata data set contains the statewide student growth percentiles as well as the median growth percentile for each course. It is a large file that will take some time to download.