Data sgp leverages longitudinal student assessment data to produce statistical growth plots (SGP) which measure students’ relative progress compared to academic peers with similar prior test scores. This information can be shared in percentile terms that are familiar to teachers and parents.
SGPs provide a useful metric for educators and families, but the calculations required to generate them can be complex. This is especially true if a student’s test score history contains multiple tests from different testing windows or subject areas. In addition, the growth estimates may be vulnerable to spurious correlations between the student’s prior assessment score and a variety of variables including school or teacher characteristics or the design of the baseline cohort.
In order to address these challenges, the OSPI team developed a new approach for producing SGPs that enables the calculation of a single estimate of a student’s current growth. This new SGP is called a “current” growth score and is reported on a 1 to 99 scale, with higher numbers indicating more growth than lower ones. A current SGP score of 75 indicates that a student’s performance is about as good as about 75% of academically-similar students.
The current growth score is calculated using up to five years of a student’s test score history, including the Badger year. The SGP displayed for a student in the graphic above is for the 2015-16 academic year.
Educators can use individual student SGPs to highlight strengths and areas for improvement in their instruction. Educators can also use SGP data to inform their student learning outcomes (SLOs) process and district-wide continuous improvement efforts. Educators should share their students’ SGPs with their families, to enrich the picture of student achievement and provide context about a student’s educational experience.
While SGPs are an important and valuable metric for educators and families, they are not intended to replace value-added scores as part of the state accountability system. State law requires value-added growth scores to be used for purposes of evaluating schools and districts. The State Accountability System is expected to transition to a fully-reformed SLO system in 2022.
A growing body of research shows that SGPs are a more valid and reliable measurement for student progress than the traditional standardized test scores alone. The data sgp website provides easy access to SGPs for all students in the state, so that educators can begin to incorporate these new measures into their classroom practice.
The data sgp package is written in the open source programming language R. It is compatible with both Windows and OSX and is freely available for download. Running SGP analyses requires a basic level of familiarity with R. The package comes with an sgpData spreadsheet that is formatted for SGP analyses. This spreadsheet, as well as the lower level functions studentGrowthPercentiles and studentGrowthProjections, require WIDE formatted data. The higher level wrapper functions, however, utilize the LONG data format for operationally-significant analyses. Please refer to the sgpData vignette for additional guidance on preparing data for SGP analyses.