The method of acquiring optimal discrete-valued attribute by dividing and grouping continuous-valued attribute in multi-institutional radiation oncology database. - Hiroko Kou; Hajime Harauchi; Akihiro Takemura; M. Iinuma; T. Kondou; Kiyonari Inamura; Hodaka Numasaki; Y. Kumazaki; M. Isibasi (CARS, 2001)