PT - JOURNAL ARTICLE ED - BMJ Publishing Group Ltd TI - Purpose and procedure AID - 10.1136/ebm.14.3.65 DP - 2009 Jun 01 TA - Evidence Based Medicine PG - 65--65 VI - 14 IP - 3 4099 - http://ebm.bmj.com/content/14/3/65.short 4100 - http://ebm.bmj.com/content/14/3/65.full SO - Evid Based Med2009 Jun 01; 14