RT Journal Article SR Electronic T1 Cost benefit analysis consists of weak definitions on both sides of the equation (Lowell Levin) JF Journal of Epidemiology and Community Health JO J Epidemiol Community Health FD BMJ Publishing Group Ltd SP 14 OP 14 VO 59 IS 1 A1 Ashton, John R YR 2005 UL http://jech.bmj.com/content/59/1/14.abstract AB