A Google Sheet + Gapps Script that automatically converts GradeCam export data (or manually entered multiple choice data - specifically course name, student name, and a single cell list of missed questions) to user defined standard scores (defined perquestion) with rubric customization support.
The current iteration of the file (V1.3) can be copied at the following link:
https://docs.google.com/spreadsheets/d/1-kAW5-Xnb7klKZXmb81nRDCgCbLu4OIqziNHNeXvZ6A/copy
I'm not aware of a nice way to import the actual code into GIT, so I will only link the existing program for now. Please mind the GNUGPL3.0.
Please note that using only multiple choice testing to assess a standard is not a very accurate method of assessment. A holistic standard score requires updating standard scores rather than overwriting them or averaging them. This program is intended to simplify a PART of the grading process; good standards-based grading requires multiple forms of assessment over time. I (and current cognitive science-based pedagogical research) strongly suggest using multiple forms of assessment to get a holistic view of student abilities where possible.
That said, you might like to use this nifty tool to automatically enter your grades into your gradebook once you've converted the scores to standard scores and adjusted to include addditional assessment.