Meta-analysis for comparative environmental case studies : methodological issues

Meta-analysis: introduction and scope Meta-analysis is increasingly recognized as a potentially important analytical framework for comparative research that aims to draw inferences on common issues with different but allied empirical backgrounds (Hedges and Olkin, 1985). The purpose of meta-analysis is to combine findings from separate but largely similar studies (in terms of subjects, hypotheses, phenomena, etc.). Such studies may be suitable for the application of a variety of analysis techniques (common literature review, formal statistical approaches, etc.) for combining, comparing, selecting or seeking out common elements, relevant results, cumulative properties etc. from a broad set of individual cases (see Button and Jongma, 1995). The aim of this paper is to illustrate and tackle some fundamental questions related to the specific methodological complexities inherent in meta-analysis (techniques to be adopted, selection of case studies, etc.) with particular reference to syntheses in the field of environmental economics. For this purpose we identify six different but interconnected levels of analysis, which, in our opinion, are particularly important both from a purely methodological point of view, and for operative and interpretative reasons. In the following sections we will analyse the specific problems and objectives related to each of these stages by underlining their most relevant methodological aspects, also in relation to the principal objectives of the analytical synthesis. The principal aims of meta-analysis may be summarized as follows: