RT Journal Article SR Electronic T1 Developing valid cost effectiveness guidelines: a methodological report from the North of England evidence based guideline development project JF Quality in Health Care JO Qual Health Care FD BMJ Publishing Group Ltd SP 127 OP 132 DO 10.1136/qhc.9.2.127 VO 9 IS 2 A1 Martin Eccles A1 James Mason A1 Nick Freemantle YR 2000 UL http://qualitysafety.bmj.com/content/9/2/127.abstract AB