Student Growth Percentiles (SGP) measure the progress of students compared to their academic peers on statewide assessments. Average SGPs are reported for schools, districts, and student subgroups. SGPs are more sensitive to classroom composition than value-added models (VAM).
Student growth percentiles are calculated for each student in a school or district based on their performance on state tests in grades 3-8, high school biology, and introductory physics. The SGPs are compared to the mean (average) of the state and to the national norm.
SGP data is collected by the districts using their course roster submission to NJ SMART during the summer following each year’s statewide assessment. SGPs are then reported to the state and district by the end of October each year. The state then publishes the SGP scores for each student on their website.
Data preparation is critical for running SGP analyses. Most errors encountered in the analysis process revert back to issues with data preparation so it is important that any person conducting SGP analyses understand the necessary steps for data preparation.
The SGPdata package provides 4 examplar data sets for use with SGP calculations. The first, sgpData, specifies data in the WIDE format that’s used with the lower level SGP functions like studentGrowthPercentiles and studentGrowthProjections. The other two, sgpData_LONG and sgptData_LONG, specify data in the LONG format that’s used by higher level SGP functions like abcSGP, prepareSGP, and analyzeSGP. It’s recommended that any analyses that will be run operationally utilize the LONG format since it offers numerous data management benefits over the WIDE format.
To use the SGPdata package a computer running the R software environment must be available. R is available for Windows, OSX, and Linux and is open source so it can be compiled for just about any operating system. It is also recommended that any user of the SGPdata package familiarize themselves with the basics of the R software environment prior to attempting to use it.
SGPs provide information about the relative ranking of a student’s academic performance but do not determine whether the education system would deem that level of performance adequate. SGPs also do not provide any information about the amount of growth or whether it was sufficient. It is important that stakeholders understand the limitations of SGPs and how they should be interpreted. SGPs should be considered alongside other student performance indicators when making decisions about educational programs and practices.