PT - JOURNAL ARTICLE ED - , TI - Purpose and procedure AID - 10.1136/ebm.6.2.34 DP - 2001 Mar 01 TA - Evidence Based Medicine PG - 34--34 VI - 6 IP - 2 4099 - http://ebm.bmj.com/content/6/2/34.short 4100 - http://ebm.bmj.com/content/6/2/34.full SO - Evid Based Med2001 Mar 01; 6