PT - JOURNAL ARTICLE ED - , TI - Purpose and procedure AID - 10.1136/ebm.10.1.2 DP - 2005 Feb 01 TA - Evidence Based Medicine PG - 2--2 VI - 10 IP - 1 4099 - http://ebm.bmj.com/content/10/1/2.short 4100 - http://ebm.bmj.com/content/10/1/2.full SO - Evid Based Med2005 Feb 01; 10