title: Confounding and cofactors: the limits of observational epidemiology.
authors.forename: G P
authors.initials: GP
authors.lastname: Garnett
mesh_terms: D015986:Confounding Factors, Epidemiologic; D004812:Epidemiologic Methods; D015658:HIV Infections / Q000453:epidemiology / Q000635:transmission; D006291:Health Policy; D006801:Humans; D012749:Sexually Transmitted Diseases / Q000453:epidemiology* / Q000635:transmission*