Data mining (DM) is the process of selecting, exploring and modeling large amounts of data in order to discover unknown patterns or relationships which provide a clear and useful result to data analyst [1]. In today technological era, millions of bytes are created within a small fragment of time. Analyzing such vast amount of data manually is beyond the scope of a human being. In such scenario data mining tools and methods give an opportunity to discover knowledge hidden in large databases. This knowledge might be useful for the user or may be a waste. This decision of usefulness of the discovered knowledge is decided based on some evaluation criteria. The most common evaluation criteria is to measure four parameters i.e. true positive, true negative, false positive and false negative and calculate the efficiency of the data mining technique being applied.