Deep Thought is a logic tutor where students practice constructing deductive logic proofs. Within Deep Thought is a data-driven mastery learning system (DDML), which calculates student proficiency based on rule scores weighted by expert-decided weights in order to assign problem sets of appropriate difficulty. In this study, we designed and tested a data-driven proficiency profiler (DDPP) method in order to calculate student proficiency without expert involvement. The DDPP determines student proficiency by comparing relevant student rule scores to previous students who behaved similarly in the tutor and successfully completed it. This method was compared to the original DDML method, proficiency based on average rule scores, and proficiency based on minimum rule scores. Our testing has shown that while the DDPP has the potential to accurately calculate student proficiency, more data is required to improve it. [For complete proceedings, see ED560503.]