ACT Growth Modeling Resources
Growth models use longitudinal assessment data to monitor the progress of students and schools. The Student Growth Percentile (SGP) model describes how well a student performed relative to peers with similar score histories. SGPs provide a normative measure of growth, describing growth relative to other students. SGPs can be used to address important questions such as:
- How much growth is needed to become on target for college and career readiness?
- How did my student’s growth compare to other students nationally?
- How much does growth in my school vary across subject areas, grade levels, and student subgroups?
- Has growth at my school improved over time?
Resources for SGPs are provided for ACT assessments, including ACT Aspire Summative, PreACT, and the ACT test. The resources provide a means to measure growth across assessments (e.g., ACT Aspire Summative to PreACT, ACT Aspire Summative to ACT, and PreACT to ACT). Below, SGP “lookup” tables are provided for:
- ACT Aspire for grades 3-10.
- ACT Aspire grade 9 to PreACT grade 10
- ACT Aspire grade 10 to ACT grade 11
- PreACT grade 10 to ACT grade 11
- ACT grade 11 to ACT grade 12
The tables provide the SGP value (ranging from 1 to 100) associated with each combination of current-year test score and prior-year test score. For example, suppose a student scored 411 on the grade 4 ACT Aspire Mathematics test and 415 on the grade 5 ACT Aspire Mathematics test one year later. His SGP would be 59 (as shown in the table below, which is an excerpt from the 2016 version of the ACT Aspire SGP lookup table).
The lookup tables provide an estimate of the SGP for each possible combination of prior year and current year test scores. The SGPs are updated periodically to reflect the most recent longitudinal data from ACT assessments. The updated SGPs are provided for all subject areas: English, mathematics, reading, science, ELA, STEM, and Composite. (Note that ELA scores are not available for PreACT because there is no Writing test).
The SGPs are estimated using quantile regression methods (Koenker, 2005) by the SGP R package (Betebenner, VanIwaarden, Domingue, Shang, 2014). While the SGP model can use multiple years of prior test scores as inputs, the lookup tables provided here are based on a single prior-year score.
The SGPs are updated over time as larger and more diverse reference groups become available. Below, the most recent SGP lookup tables are provided, along with earlier versions of the tables.
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 package version 1.2-0.0. URL.
Koenker, R. (2005). Quantile Regression. New York, NY: Cambridge University Press.