PT - JOURNAL ARTICLE ED - , TI - PURPOSE AND PROCEDURE AID - 10.1136/ebm.8.1.2 DP - 2003 Jan 01 TA - Evidence Based Medicine PG - 2--2 VI - 8 IP - 1 4099 - http://ebm.bmj.com/content/8/1/2.short 4100 - http://ebm.bmj.com/content/8/1/2.full SO - Evid Based Med2003 Jan 01; 8