The SGP package comprises classes, functions and data used to calculate student growth percentiles and projections/trajectories using large-scale longitudinal education assessment data. Students with similar academic histories are compared against one another and their individual scores adjusted according to grade and content area to determine expected percentage growth needed to reach future achievement targets. Coefficient matrices generated during this process provide scores and plots which demonstrate student progress over time.

Educators should employ SGPs to understand the strengths and weaknesses of their student populations, inform decisions regarding instruction, and set educational goals. Individual student SGPs should be shared with parents for further insight into a child’s performance as well as discussions of areas for improvement. Educators may also review grade-level or subgroup SGPs to pinpoint areas for focus; then use this data in their teacher goal setting processes. Administrators may include SGP analyses into continuous improvement processes.

SGP analysis employs R, a statistical programming language available free to Windows, Mac OSX and Linux users through its CRAN distribution. An SGP vignette and comprehensive online resources available from CRAN provide guidance for getting started with and performing SGP analyses.

SGP analysis functions require access to anonymized student assessment data. A sample LONG dataset is provided in the SGP repository’s sgptData_LONG folder, featuring 8 windows (3 windows annually) of assessment data in LONG format from three content areas for two years – including valid_CASE, CONTENT_AREA, YEAR, ID number, SCALE_SCORE grade level score and ACHIEVEMENT LEVEL variables that must all be present if running student growth and achievement plots.

As well as its analysis functions, the SGP package offers several additional tools and utilities that facilitate creating tailored reports. These include creating one report that aggregates all student aggregates or report specific groups of students directly into an Excel spreadsheet. Furthermore, it features a utility to produce a report detailing student growth percentile calculations over time for every subject and grade level.

The sgptData_INSTRUCTOR_NUMBER file provides an anonymous instructor-to-student lookup table which lists instructors related to each assessment record of a student. This data set is essential if the students’ SGP percentiles are to be understood relative to teachers with diverse educational backgrounds. It is vital that students use this data set, since their performance can be affected by factors other than academic abilities affecting a teacher’s teaching style, cohort design or baseline cohort design – errors can arise without it! In addition, SGP function summSGP_teacher_aggregates() requires this variable for every individual student in order to create reports which are more accurate and interpretable.