Data SGP is a software package that allows users to process longitudinal education assessment data. It creates statistical growth plots (SGP) which provide visual evidence of student progress relative to their academic peers. SGPs are based on students’ standardized test scores and covariate information and are calculated using the “growth standard”, established through their prior testing history. SGPs are useful in identifying high performing students, determining the level of support needed for struggling students and illustrating how much students must grow in order to reach official achievement targets/goals.
SGPs show how much a student has grown on a given standardized test score by comparing their score to that of the average student in their grade level. A SGP is measured on a 1-99 scale with higher numbers indicating more relative growth than lower ones. For example, if a student’s SGP is 75 then they have grown at least 75% as much as their academic peers.
Educators use SGPs to assess student/teacher performance and classroom instruction as well as to support research initiatives, evaluate schools/districts and inform educational decision making. It also allows teachers to identify areas that may need improvement within their classrooms and can be used to target differentiated instruction. It can also help teachers understand what is required to meet achievement goals based on a student’s current growth status, which in turn helps to articulate and communicate those goals more clearly.
While SGP analyses are powerful, they can be complex and require a fair amount of data preparation. As such, it is essential that educators have a thorough understanding of the methodologies behind SGP analyses before running them operationally year after year. Any errors encountered during data analysis usually revert back to issues with the initial data preparation stage.
To run SGP analyses, a user must have access to the free and open source statistical software environment, R. This is available for Windows, OSX and Linux and there are numerous online resources to assist with getting started. In addition to having a working knowledge of R, an understanding of the fundamentals of SGP analysis is recommended.
To prepare SGP data, a file called sgpData must be created which contains the students unique ID and 5 years of their grade level standardized tests. The sgpData file must be formatted in WIDE in order to be used by the SGP lower level functions studentGrowthPercentiles and studentGrowthProjections. For further instructions on creating and using sgpData for SGP analyses, please refer to the SGP data analysis vignette. Alternatively, LONG formatted sgpData files can be used if desired but the additional steps required for converting from WIDE to LONG are more time consuming and are not recommended for operational SGP analyses.