Data Sgp is an analysis tool for longitudinal student assessment data that creates statistical growth plots (SGPs) that provide evidence of students’ progress relative to their academic peers. It uses students’ standardized test scores with covariate information using a “growth standard”, established through prior testing history, to offer more accurate measurements of student growth than traditional percentiles.
In addition, teachers can use SGPs to help them determine if their students are growing more than, less than, or as much as expected and to identify which students may need additional support in reaching their achievement goals. SGPs are available in two formats: Window Specific SGPs that provide a comparison of a student’s current SGP with their SGP from a previous testing window and Current SGPs which offer a quick snapshot of a students’ growth over time.
The SGP package provides a series of functions, studentGrowthPercentiles and studentGrowthProjections, to perform these analyses. However, most operational SGP analyses are conducted with higher level function wrappers, abcSGP and updateSGP, that combine these 6 steps into a single function call, greatly simplifying the source code associated with these analyses.
It is essential that educators have a full understanding of the methodology behind SGPs and its underlying mathematical models and assumptions before conducting SGP analyses. To aid in this process, the SGP Package includes several tutorials and examples designed to introduce these fundamental concepts to beginning users of the software.
SGP analyses require time dependent data and most of the lower level functions that do the actual calculations, including studentGrowthPercentiles and studentsGrowthProjections, require the user to supply this in the WIDE format. The exemplar LONG format data set, sgpData and the INSTRUCTOR-STUDENT lookup file sgpData_INSTRUCTOR_NUMBER are provided to facilitate this process. The SGP vignette and the sgpData_LONG analysis script contain comprehensive documentation on how to use sgpData for SGP analyses.
Using the SGP data sets is easy and straight forward, although it is recommended that you consult the sgpData_LONG vignette for more detailed instructions on how to use the sgpData file for SGP analyses. It is also important to remember that SGP analysis can only be run on a data set that is in the correct format and that any issues encountered while running an analysis typically revert back to problems in the initial stages of data preparation.