PT - JOURNAL ARTICLE ED - , TI - Purpose and procedure AID - 10.1136/ebm.11.4.97 DP - 2006 Aug 01 TA - Evidence Based Medicine PG - 97--97 VI - 11 IP - 4 4099 - http://ebm.bmj.com/content/11/4/97.short 4100 - http://ebm.bmj.com/content/11/4/97.full SO - Evid Based Med2006 Aug 01; 11