How to perform grade distribution analysis
Preparing your data
You will need to start by exporting your class grades, most learning management systems will let you download a .csv (spreadsheet) file with these data. Open this in excel or google sheets, and we can view how each student performed on each assignment. If you've set up your LMS to allocate your students to different sections, then you will need to create a new column of data that shows which grader is responsible for each student. I've outlined this process below in Figures 1 and 2.
Figure 1. Here is a de-identified gradebook of ours. Notice that there is a column for each assignment, and that one column includes a list of the section that each student is in.
Figure 2. A) In order to add TAs (or graders) to our list I first create a lookup list that indexes what classes are graded by each TA. B) I then create a new column that is filled with the formula:
=INDEX($B$1:$B$15, MATCH(G2,$A$1:$A$15,0)).
The purpose of this formula is to index (look up a value) between the range B1 and B15 (The TAs). The $ are used so that these values are fixed when the formula is applied to all of the cells in the TA column. =INDEX( returns a value in this first listed section that corresponds to the row specified by the MATCH formula. After the comma that starts the second argument of the INDEX formula, I use the MATCH formula to pick out the correct row within B1-B15 that I want to return the value for. As its name implies, MATCH thries to match the value in G2 (the first section number in our sheet) to the values in A1-A15. It then uses this row number in the INDEX formula.
Once I finish this formula, I double click in the small box on the lower right corner of the selected cell in blue to fill this series to the bottom of my data sheet. I now have a list of which graders graded which assignments.
Graphing the data
Now that we have our input, we can use the free graphing tools at Plot.ly to graph these data and construct box plots. You will need to make an account, but the free version is sufficient for our needs. Please follow the directions in the video below to create your graphs.
***Note: Since the release of Plot.ly 2.0, Plot.ly has restricted the export of certain graphs like the histograms I use in the video above. If you are interested in analyzing your data this free version is sufficient, but I am in the process of writing directions for how to accomplish this using free excel add ons.