ABSTRACT
In Chapter 2 to Chapter 11 we have seen how to design and analyse specific epidemiological studies. In this chapter, we discuss how to review the evidence of several studies, the totality ideally being all the available evidence on the association between the risk factor exposure and disease outcome of interest. Such reviews typically have two major aims:
1. To ascertain how much consistency the exposure-outcome relationship has across different studies. This addresses one of the key conditions for establishing causality in epidemiology (Section 1.6.3) — that of consistency, at least in a qualitative sense, in different study settings.
