Data SGP leverages longitudinal student assessment data to produce statistical growth plots (SGPs). An SGP is a graph that shows a students’ progress over time, compared to academic peers. It is a valuable tool for educators and parents to use in their classrooms and homes. It can help them to see how a student is progressing and whether or not they are on track to graduate from high school. An SGP can also help them identify the areas in which a student needs further instruction and support.
SGP analyses are complex and involve the manipulation of large amounts of data. It is important to ensure that your calculations are correct and not influenced by spurious correlations. These correlations may be caused by the choice of teacher or school, by the design of the baseline cohort, or by the number of years in the data set. Ideally, your data should be analyzed in the context of other student and teacher-level characteristics. This will help to reduce the risk of misinterpreting the results of your SGP.
To help you avoid these mistakes, we have created the SGP package with wrapper functions, abcSGP and updateSGP, that simplify the source code associated with an SGP analysis. These functions “wrap” the lower level studentGrowthPercentiles and studentGrowthProjections functions. In operational SGP analyses, these higher level functions are almost always used together with the LONG data, sgpData_LONG and the INSTRUCTOR-STUDENT lookup file sgpData_INSTRUCTOR_NUMBER.
The sgpData_LONG and sgpData_INSTRUCTOR_NUMBER files contain the SGP model inputs needed to calculate the students’ growth percentiles and projections. These inputs are not a complete list of the variables that are required to produce an SGP, but they are sufficient for most operational analyses. These files are available from the SGP website, or they can be downloaded directly from the SGP package.
Before you use the sgpData files, spend some time formatting the columns to make them more useful. For example, change the decimal point format to a value that is easier for you to read (e.g., three decimal points for BA, two decimal points for ERA and WHIP). This will help you to interpret the data more easily.
To prevent errors, be sure to save your sgpData_LONG and SGP model output in a separate folder from the sgpData_INSTRUCTOR_NUMBER and sgpModel_INSTRUCTOR files. This will protect the outputs from the possible accidental deletion of these files. It will also allow you to easily refer back to the raw data and sgpModel_INSTRUCTOR input files, and it will make it easier to understand your results. To do this, open the SGP model output file in Excel. You will find the sgpData_LONG and output file names in the SGP output pane. To save the SGP output as a new spreadsheet file, click the File menu and select Save As. Then give the file a name such as SGP Calc output. This file will be ready for your next SGP calculation. The SGP Calc file will automatically update with the latest results from your sgpData_LONG spreadsheet.