ABSTRACT
This is the second of the two chapters that outline the evidence base for the remainder of this book. This chapter explains why the findings are original and different to what other commentators often merely assume to be true. The first part of the chapter concerns several systematic reviews of prior evidence that form the basis for much of the subsequent chapters. It outlines how material was sought, assessed and synthesised. In general, previous work has been classified in terms of the four components of the causal model (Chapter 1). Only work that does not address one of these components was excluded from consideration. This multi-method and multi-scale approach does lead to a few problems however, especially where authors have over-claimed or not provided sufficient description of the evidence for their claims. The second part of this chapter provides a justification, with examples, for excluding some apparently relevant studies from the research syntheses presented in later chapters. The chapter then moves on to the primary and in-depth datasets used in this book, and any specific ways in which such data has been analysed. It is not the purpose of this book to describe the methods involved in detail, and so readers must rely to some extent on the copious references.
