A student’s growth percentile is a measure of how much their performance on a MCAS assessment improved compared to their “academic peers.” An SGP tells us whether a student grew more than, less than, or about the same as their academic peers—in other words, if a student’s score on an assessment increased or decreased compared to that of an average student in their grade. A student’s SGP can be used alongside their scaled scores and achievement levels to give a more complete picture of how they’re performing in school.
SGPs are calculated using up to two years of historical MCAS data. A student’s score is compared to the score of academic peers with similar MCAS test history, and a statistical method called quantile regression places those students on a normative scale that can be used to identify their relative performance. Academic peers can include students from different schools, grades, and demographic groups (e.g., gender, income) as long as they have a similar MCAS history and are enrolled in the same grade.
The state’s SGPs are used to create reports that teachers, administrators, and families can use to understand how students performed on MCAS assessments in past years, compare their results to those of their academic peers, and determine if they are making progress towards achieving their achievement goals. The reports can be accessed through the BAA Secure Site. The State uses the SGP data to produce two types of reports: window specific SGPs, which can be used to compare or report student growth for particular windows of time, and current SGPs, which provide a quick check-in on how a student’s progress is going from one year to the next.
It’s important to remember that SGPs are based on comparative performance and that changes in SGPs from one year to the next can only be meaningfully interpreted by looking at the change in the student’s percentile ranking, not the raw number. For example, a student with an SGP of 75 means that the student scored higher than or equal to 75% of their academic peers.
As a free, open source software package, SGP analyses can be run on a variety of operating systems and devices. However, to use the program, you will need a computer running R. A free version of R is available for Windows, Mac, and Linux, and can be downloaded from CRAN. We recommend taking some time to familiarize yourself with the software before diving in to SGP analyses. You can also find a wealth of R resources online. SGP vignettes are designed to guide users through the various functions and analysis tools available within the software. However, a full understanding of the software will likely require a significant amount of additional research. If you have any questions about SGP vignettes, or are unable to find the information you need, please contact us. We will do our best to answer your question as quickly as possible.