This is a classic reference that reminds us that even with all the objective methods developed for systematic overviews, there is still a core of choices that are largely subjective.
Mayor S. Row over breast cancer screening shows that scientists bring some subjectivity into their work. BMJ. 2001;323(7319):956. Excerpt: “The difficulty of getting scientists to reach a consensus on their interpretations of trial data was illustrated last week when two reviewers for the Cochrane Breast Cancer Group published their own review of mammography screening trials after editors from the group had disagreed with some of their conclusions.” Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1121506/. Accessed November 24, 2013.