Although confounding is an important problem of cohort studies, its effects can be minimised to enable valid comparison. PMC ID: PMC556348 (April 23, 2005)
Sharon-Lise Normand
British Medical Journal
2005
Mamdani M, Sykora K, Li P, et al.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC556348/