Data sgp is a set of classes, functions and data that are used to calculate student growth percentiles (SGP). These percentiles provide a way for students to be fairly compared, even though they may enter school at different levels. This makes it possible for teachers and administrators to identify areas where students are falling behind and make necessary improvements.
SGPs estimate a student’s growth based on how they perform in comparison to their academic peers with similar prior test scores. This is a more accurate measure of achievement than standard or scaled test scores and allows the results to be reported in percentile terms that are familiar to most teachers and parents.
Using longitudinal student assessment data, SGPs are estimated using least squares regression models with the goal of creating an estimate of the true latent achievement trait underlying the test score covariates. The estimated SGP is then compared against growth standards established using student and teacher evaluation criteria.
A SGP can be calculated for any student with a sufficient number of assessments in the current and one previous testing window. This requires that the most recent assessment be taken within the past 18 months and that at least two prior assessments be available to use for estimating the student’s growth. The most recent assessment must be a Star assessment and at least one prior assessment must be from an approved state test or other approved national testing program.
There are several ways to format longitudinal student data for use with SGPs, but the simplest way is to use the exemplar WIDE and LONG formats provided with the sgpdata package when installing it. The lower level SGP function studentGrowthPercentiles and the higher level wrapper function studentGrowthProjections can be used with either format, but it is typically better to use LONG format if you plan on running these analyses operationally year after year.
The SGP database is updated regularly to provide the most current information on student growth, but there are a number of factors that can impact whether or not a student’s SGP will increase or decrease over time. This is particularly the case when the student moves to a new school or subject, as it takes time for the SGP of a new assessment to catch up to the SGP of the old assessment. This is why it’s important for SGP administrators to monitor their schools’ SGPs and update them frequently. This ensures that they are able to report the most accurate information to their stakeholders.