studentGrowthPercentiles and studentGrowthProjections, and numerous higher level functions
that make use of them including: prepareSGP, analyzeSGP, combineSGP, summarizeSGP, and reportSGP
used to calculate and report student growth percentiles and percentile growth projections/trajectories for students using large scale, longitudinal assessment data.
These norm referenced growth values are currently used in a number of state testing and accountability systems. The functions employ quantile
regression (using the quantreg package) to estimate the conditional density for current achievement using each student's achievement history.
Percentile growth projections/trajectories are calculated using the coefficient matrices derived from the student growth percentile analyses. These quantities
are summarized in a variety of ways to describe student growth. As of the 0.0-7.0 release, the package also includes functions (e.g.,
bubblePlot and studentGrowthPlot) to produce graphical representations associated with the student growth percentile analyses.sgpData for an example data set. Batch R syntax for performing analyses across all grades and years is
provided in the examples of the studentGrowthPercentiles and studentGrowthProjections using the higher level functions
prepareSGP, analyzeSGP, combineSGP, summarizeSGP, and reportSGP.Betebenner, D. W. (2008). Toward a normative understanding of student growth. In K. E. Ryan & L. A. Shepard (Eds.), The Future of Test Based Accountability (pp. 155-170). New York: Routledge.
Koenker, R. (2005). Quantile regression. Cambridge: Cambridge University Press.