Rough set theory is a tool for studying imprecision, vagueness, and uncertainty in data analysis. It focuses on discovering patterns, rules, and knowledge in large pools of data. The theory has its origin in the great research effort in the 1970’s by Polish mathematicians and computer scientists in the analysis and representation of information systems. The concept of a rough set was put forward by Dr. Zdzislaw Pawlak in 1982, and was later advanced into various data mining applications by Dr. Andrzej Skowron. The theory of rough sets has been used for numerous applications in medicine, pharmacology, engineering, manufacturing, and banking.