Cohort studies can provide valuable information unavailable from randomised trials, but readers need to be alert to possible flaws. PMC ID: PMC556167 (April 16, 2005)
Sharon-Lise Normand
British Medical Journal
2005
Gurwitz JH, Sykora K, Mamdani M, et al.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC556167/