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About SGP

An R Package for the calculation & visualization of student growth percentiles and percentile growth trajectories/projections

The SGP Package (Betebenner, VanIwaarden, Domingue, Shang, 2014) is an open source package built for the open source R software environment (R Development Core Team, 2014). The classes, functions and data within the SGP package are used to calculate student growth percentiles and percentile growth trajectories/projections using large scale, longitudinal assessment data. The methodology uses quantile regression to estimate the conditional density associated associated with each student’s achievement history. Percentile growth projections/trajectories are calculated using the coefficient matrices derived from the quantile regression analyses and specify the percentile growth required for students to reach future achievement targets.

Team Members

The SGP Package is crafted with :heart: by:

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Install the latest stable release from CRAN


Install latest development release from Github :octocat:

install_github("SGP", "CenterForAssessment")

To install from Github you might need: Windows: Rtools (, OS X: xcode (from the app store), Linux: apt-get install r-base-dev (or similar).

To use the SGP Package

The SGP Package Wiki contains instructions on how to prepare data and run SGP analyses.


Betebenner, D. W., VanIwaarden, A., Domingue, B., and Shang, Y. (2014). SGP: An R Package for the Calculation and Visualization of Student Growth Percentiles & Percentile Growth Trajectories.

R Development Core Team (2014). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. 3-900051-07-0.

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