3 ﹒王家良主编.临床流行病学— — —临床科研设计、测量与评价.第二版.上海:上海科技出版社,2001.4 ﹒ Edwcod M . Critical appraisal of epidemiological studies and clinical trials . 2ndedition . London:Ox ford Univ . press,1998. ......