If you’re working with longitudinal (time dependent) student assessment data, the data sgp package offers both lower level functions that perform calculations as well as higher-level wrappers that make complex analyses simpler. While certain of these functions, including studentGrowthPercentiles and studentGrowthProjections require WIDE formatted data sets, other functions (and wrappers) can utilize LONG formats instead. We strongly suggest opting for long format data sets as this will offer greater benefits in terms of preparation and storage space compared to WIDE formats.
Data SGP is a set of tools for analyzing longitudinal data and producing student growth and achievement reports. It employs an innovative calculation technique for SGP that accounts for measurement error inherent in standardised test scores; unlike other measures of student performance such as mean and median scores which directly reflect test performance, SGP indirectly measures students’ true latent achievement traits using recent and prior test scores along with covariates associated with those tests.
There are various factors that affect the accuracy of SGP estimates, such as model complexity and availability of student-level information such as demographics. Most errors that arise in calculating SGP can be linked back to data preparation issues; so it is critical that quality data be gathered, followed by proper data analysis procedures.
Student Growth Percentiles
When compared against their academic peers, student growth percentiles provide the ideal measure of relative student performance. These percentages illustrate average student progress over time compared to their academic peers and can be calculated for individuals as well as groups by averaging their SGPs across their collective membership.
Data SGP also provides growth trend charts that allow teachers and parents to monitor students’ progress over time, helping to identify patterns such as sudden decrease or increase in performance over time. These charts can also assist teachers and parents in monitoring whether a sudden decline or steady increase is occurring among their pupils.
In general, taking more tests will increase student grade point average (SGP). This is because more time spent taking assessments means more opportunity to improve test scores. Conversely, taking less frequent assessments will likely lower a student’s SGP. Therefore, schools must carefully consider all the advantages and disadvantages when selecting testing schedules for their students. The ideal testing schedule depends on both the number and frequency of assessments a student has completed in a given period, as well as how long there has been between each one. A school should strive for consistency when setting its student testing schedule to ensure accurate estimates from SGP testing results.