RT Journal Article SR Electronic T1 Correction: What does expert opinion in guidelines mean? a meta-epidemiological study JF BMJ Evidence-Based Medicine JO BMJ EBM FD BMJ Publishing Group Ltd SP 78 OP 78 DO 10.1136/ebmed-2017-110798corr1 VO 23 IS 2 YR 2018 UL http://ebm.bmj.com/content/23/2/78.abstract AB