RT Journal Article SR Electronic T1 Why Meta-Analysis? JF Regional Anesthesia & Pain Medicine JO Reg Anesth Pain Med FD BMJ Publishing Group Ltd SP 3 OP 5 DO 10.1053/rapm.2002.29109 VO 27 IS 1 A1 Halpern, Stephen YR 2002 UL http://rapm.bmj.com/content/27/1/3.abstract