To provide a data mining method effective to a problem in the real world by enabling the finding out of a rule from large-scale or various data, a noise, or imperfect data.

This method comprises a combination of a generalized distribution table GDT and a rough set(RS) theory, and covers all theories of logic, aggregate and probability. The GDT is used to form a probability reference for evaluating the imperfectness/ambiguity of data and the strength of the found rule, and the rough set theory is used to extract the rule or narrow a minimum rule set covering all actual examples from strong rules.