While the various types of reviews outlined above each have different audiences, they are all essentially ‘narrative literature reviews’ (Neuman, 2002) that offer a ‘tour’ of research in the area selected by the author. They do not present, nor do they aspire to, a comprehensive coverage of the area, and they make no distinction between different types of works (e.g. refereed journal article, book chapter, conference paper). As

Systematic review and meta-evaluation are both forms of what is increasingly becoming known as research synthesis (see Weed, 2005b, for a review of a range of synthesis approaches). Systematic review as a method of synthesis is widespread in the fields of medicine (Cook et al., 1997), psychology (Biddle et al., 2003), and policy (Pawson 2002) and is used in these fields to ensure that treatment, interventions, and initiatives are based on the ‘best evidence (Davies et al., 1999). However, it can also be used to assess the nature and extent of knowledge in an area (e.g. Weed et al., 2005). Systematic reviews differ from traditional narrative reviews in that they provide objective, replicable, systematic, and comprehensive coverage of a defined area. Klassen et al. (1998, p. 701) define the systematic review as follows:

A systematic review is a review in which there is a comprehensive search for relevant studies on a specific topic, and those identified are then appraised and synthesised according to a pre-determined explicit method.