Data sgp is a package for conducting longitudinal analyses on student assessment data using the R software environment. R is free, open source and runs on many operating systems. Using this package requires a working knowledge of the R programming language and some familiarity with SGP data sets. The sgpdata package installed when you install this package contains an example WIDE and LONG formatted data set (sgpData_WIDE and sgpData_LONG, respectively) to assist in setting up your own SGP analyses. Most higher level functions are designed to work with LONG formatted data and often assume the presence of state specific meta-data embedded in the sgpData set, referred to as SGPstateData, when calculating SGPs.
SGPs are calculated by comparing students to similar students on a particular test with a given score history. For example, Student A and Student B scored the same on this year’s MCAS test in a subject area. However, they have different SGPs because they likely had different academic peer groups in previous MCAS administrations for this particular subject area.
Individual SGPs can be a valuable piece of information for parents, educators and administrators. They can help identify areas of strength and target areas for improvement. This information can be used in the educator’s Student Learning Objectives process, and school and district leaders can use it to inform their continuous improvement plans.
Generally, mean SGPs across the state are expected to have an approximate bell-shaped distribution with an equal number of students at each percentile (the diagram on the right shows groupings of 10 or deciles). It is important to keep in mind that a median SGP may be slightly higher than 50 because norms are usually established using data from only one year of testing and half of students in the state have growth below 50.
The SGPs produced by DPI are reported on the student-level dashboard. However, mean SGPs are not reported in the federal accountability system (APR) or on the Accountability Report Cards, and will not be incorporated into the value-added calculations required by state law for teacher evaluation.
While value-added calculations are currently the only way for teachers to be evaluated in their performance, mean SGPs will be used as part of a new federal accountability system in the future. In the meantime, we continue to focus on our efforts toward developing and improving our current state evaluation system.
To learn more about our vision for the new evaluation system, visit our Vision page.
This is a draft version of this document. We welcome feedback and questions. If you have questions or comments, please contact us.
A final, completed version of this guide will be published shortly. In the meantime, this draft is a good resource to understand the purpose and process of SGPs for both educators and parents.
SGPs are not the only measure of student achievement, but they should be an integral component of a holistic evaluation system. We look forward to incorporating these tools into our comprehensive evaluation system, ensuring that all students are on the path to success.