What it contains right now is a SUS calculator (with a Cronbach reliability test) with a sample SUS scoresheet. It also has a paired t test, one sample t test and two sample t test incase you wish to compare SUS scores of different designs or compare a score to a benchmark.
You can take the users responses (range of 1-5) and enter them on the sheet. You can then select the range of the responses with your mouse (or enter them manually) in the add-on and click ‘update range’.
By clicking on run test, you get the average SUS score for that set of responses as well as the internal reliability score (between 0 to 1).
Optionally if you want to see the SUS score for each respondent, you can select a cell which can display the SUS score column and when you click run test, it will update that column with the individual SUS scores.
I will also be making some video tutorials soon!