Data sgp is an analysis tool for longitudinal student assessment data that creates statistical growth plots (SGP) that provide visual evidence of students’ progress relative to academic peers. Unlike traditional percentile scores, SGPs account for students’ varying starting points on the achievement scale and provide educators with more accurate information regarding student performance.
SGPs are calculated using students’ standardized test scores and covariate information that is based on their prior testing history. SGPs allow teachers to identify students who may need additional support, differentiate classroom instruction for high-performing students, and monitor the progress of all students over time.
Educators who use SGP can also make more informed decisions about their students and their school or district’s overall performance. SGP reports include state specific growth curves that describe the percentage of students who are performing above or below their expected growth. These reports can be used to determine whether a school is on track or falling behind in the race to meet its goals for student achievement.
To run SGP analyses teachers and administrators need a computer running the open source software R. The software is available for Window, OSX, and Linux and is a good choice for analyzing student data. If you are unfamiliar with the program, we suggest spending some time learning how to use it before diving into SGP analyses.
Once you have a computer with R installed, the process of creating SGPs is straightforward. The lower level functions that do the calculations, studentGrowthPercentiles and studentGrowthProjections, require WIDE formatted data. Higher level functions, that act as wrappers for the lower level functions, can be run with either WIDE or LONG formatted data. If you are running anything but the simplest of analyses, we recommend supplying your data in the LONG format as many of the package’s more advanced capabilities are built around it.
A SGP score is a number between 1 and 99 that indicates how much a student’s standardized test score has changed in relation to their academic peers. For example, a student with a SGP of 85 means that they have shown more growth than 85 percent of their academic peers.
To determine a SGP, a student’s scale score on a state assessment is compared to the growth standards established for that particular year. The SGP is then calculated by dividing the change in the student’s score by the standard deviation of the score range. For example, a student with whose scale score falls in the 90th percentile will have an SGP of 89. The more the student’s score increases, the greater their SGP will be. For a more detailed description of how SGPs are calculated, see the technical resources on the SGP website. SGPs can be reported for Window Specific SGPs, which are used to compare or report student growth over a given window, and Current SGPs, which are used to quickly check in on progress over short periods of time.
