PT - JOURNAL ARTICLE ED - , TI - Purpose and procedure AID - 10.1136/ebm.12.3.65 DP - 2007 Jun 01 TA - Evidence Based Medicine PG - 65--65 VI - 12 IP - 3 4099 - http://ebm.bmj.com/content/12/3/65.short 4100 - http://ebm.bmj.com/content/12/3/65.full SO - Evid Based Med2007 Jun 01; 12