PT - JOURNAL ARTICLE ED - BMJ Publishing Group Ltd TI - Purpose and procedure AID - 10.1136/ebm.10.6.161 DP - 2005 Dec 01 TA - Evidence Based Medicine PG - 161--161 VI - 10 IP - 6 4099 - http://ebm.bmj.com/content/10/6/161.short 4100 - http://ebm.bmj.com/content/10/6/161.full SO - Evid Based Med2005 Dec 01; 10