RT Journal Article SR Electronic T1 Uncontrolled before-after studies: discouraged by Cochrane and the EMJ JF Emergency Medicine Journal JO Emerg Med J FD BMJ Publishing Group Ltd and the British Association for Accident & Emergency Medicine SP 507 OP 508 DO 10.1136/emermed-2015-204761 VO 32 IS 7 A1 Steve Goodacre YR 2015 UL http://emj.bmj.com/content/32/7/507.abstract AB