The Campbell Collaboration has published a guide to information retrieval for systematic reviews: "Searching for studies: a guide to information retrieval for Campbell systematic reviews".
The guide aims to provide general guidance to reviewers and to establish minimum standards for key information retrieval tasks. Although the guide speaks specifically to individuals planning to conduct a Campbell review, the policies, procedures and guidelines are applicable to anyone interested in implementing information retrieval methods that maximise coverage and minimise bias during the information retrieval process. It will also be useful to librarians who may wish to consult this guide as a reference source.
The guide outlines some general issues in searching for studies; describes the main sources of potential studies; and discusses how to plan the search process, design and carry out search strategies, manage references found during the search process and correctly document and report the search process.
An essential part of the systematic review process
The guide's fundamental premise is that information retrieval is an essential component of the systematic review process, analogous to the data collection phase of a primary research study, and requires the expertise of a trial search coordinator, an information specialist or a librarian. A thorough and unbiased compilation of all potentially relevant studies is one of the key characteristics of a systematic review and if the literature located is unrepresentative of the population of completed studies, the remainder of the review process will be compromised.
"Searching for studies" is based on chapter 6 of the Cochrane Handbook. The authors would like to thank Carol Lefevbre, Eric Manheimer and Julie Glanville for kind permission to do so.