Applied Mathematical Sciences, Vol. 3, 2009, no. 7, 297 - 316 Using Affinity Set on Finding the Key Attributes of Delayed Diagnosis Yuh-Wen Chen Institute of Industrial Engineering and Management of Technology, Da-Yeh University, 112 Shan-Jeau Rd., Da-Tsuen, Chang-Hwa 51505, Taiwan profchen@mail.dyu.edu.tw Moussa Larbani Dept. of Busness Administration, Kainan University, No 1, Kainan Road, 338 Taoyuan County, Taiwan larbani61@hotmail.com Dept. of Business Administration, Kulliyyah of Economics and Management Sciences IIUM University, Jalan Gombak, 53100 Kuala Lumpur, Malaysia Chih-Min Shen Institute of Industrial Engineering and Management of Technology Da-Yeh University, 112 Shan-Jeau Rd., Da-Tsuen Chang-Hwa 51505, Taiwan Chao-Wen Chen Department of Trauma, Hospital of Kaohsiung Medical University 100 Shi-Chuan 1st Rd., San Ming District, Kaohsiung City, Taiwan Abstract According to Institute of Medicine investigation report in the U.S., there are at least