Data SGP
Data SGP, or student growth percentiles (SGPs), are a measure of students’ achievement gains. SGPs are calculated by comparing students’ test scores from one year to the next, ranked against students with similar previous academic performance. This allows for the comparison of students’ achievement in a variety of ways, including by subgroups like gender, race/ethnicity and socioeconomic status.
SGPs are estimated using a technique called quantile regression. The underlying method is very mathematical and computationally complex but it provides a more interpretable and less biased result than many other models such as value-added models. Moreover, SGPs are based on percentile ranks that are familiar to teachers and parents, which makes them easier for teachers, administrators and policymakers to understand and use.
The sgpData table provides the raw data used to calculate SGPs and generate the student growth plots. The table consists of two columns for each student, one providing unique student identifiers and the other, a list of the teachers that the student has been assigned to during their time at the school.
Each year, the sgpData table is updated with the latest longitudinal data available from ACT. Data is weighted to more accurately reflect the population of students who take ACT assessments in the state. The tables are grouped by the subject area of the assessment – English, math, reading, science and STEM – and by grade level.
The lower level SGP functions – studentGrowthPercentiles and studentGrowthProjections – require WIDE formatted data. The higher level wrapper functions, such as prepareSGP and studentGrowthPlots, can be run with either WIDE or LONG formatted data. If you plan on running SGP analyses operationally, year after year, we recommend formatting your data in the LONG data format as it provides numerous preparation and storage benefits over WIDE data.
A Boolean argument (defaults to FALSE) indicating whether studentGrowthPlots are produced. When set to TRUE, the function sgp_studentGrowthPlots produces PDF student growth plots for each student with the following arguments:
This is not a complete vignette on SGP analysis but should provide an overview of the process of generating and displaying student growth reports. If you have any questions about this vignette or SGP in general, please reach out to us! We’re happy to help.