RT Journal Article SR Electronic T1 Teaching tip: the invisible hand of randomisation JF Evidence Based Medicine JO Evid Based Med FD BMJ Publishing Group Ltd SP 5 OP 5 DO 10.1136/ebm.11.1.5 VO 11 IS 1 A1 Sharon Sanders A1 Grad Dip Child Devel YR 2006 UL http://ebm.bmj.com/content/11/1/5.1.abstract AB