QUEST Function

I am having a great deal of trouble using the QUEST function properly. There does not seem to be much documentation on it and the published papers I have read about it are very technical and hard to understand. I currently have it implemented in my code, but if the participant gets all the questions right, it spits out a negative value. I don't think that makes sense. 


Can anyone help me understand how the Quest function works or where I can go to find information that will help me?


Thank you in advance