PT - JOURNAL ARTICLE ED - , TI - Purpose and procedure AID - 10.1136/ebmed.17.03.e3 DP - 2012 Jun 01 TA - Evidence Based Medicine PG - e3--e3 VI - 17 IP - 3 4099 - http://ebm.bmj.com/content/17/3/e3.short 4100 - http://ebm.bmj.com/content/17/3/e3.full SO - Evid Based Med2012 Jun 01; 17