Abstract
BackgroundGrey literature is an important source of information for large-scale review syntheses. However, there are many characteristics of grey literature that make it difficult to search systematically. Further, there is no ‘gold standard’ for rigorous systematic grey literature search methods and few resources on how to conduct this type of search. This paper describes systematic review search methods that were developed and applied to complete a case study systematic review of grey literature that examined guidelines for school-based breakfast programs in Canada.MethodsA grey literature search plan was developed to incorporate four different searching strategies: (1) grey literature databases, (2) customized Google search engines, (3) targeted websites, and (4) consultation with contact experts. These complementary strategies were used to minimize the risk of omitting relevant sources. Since abstracts are often unavailable in grey literature documents, items’ abstracts, executive summaries, or table of contents (whichever was available) were screened. Screening of publications’ full-text followed. Data were extracted on the organization, year published, who they were developed by, intended audience, goal/objectives of document, sources of evidence/resources cited, meals mentioned in the guidelines, and recommendations for program delivery.ResultsThe search strategies for identifying and screening publications for inclusion in the case study review was found to be manageable, comprehensive, and intuitive when applied in practice. The four search strategies of the grey literature search plan yielded 302 potentially relevant items for screening. Following the screening process, 15 publications that met all eligibility criteria remained and were included in the case study systematic review. The high-level findings of the case study systematic review are briefly described.ConclusionsThis article demonstrated a feasible and seemingly robust method for applying systematic search strategies to identify web-based resources in the grey literature. The search strategy we developed and tested is amenable to adaptation to identify other types of grey literature from other disciplines and answering a wide range of research questions. This method should be further adapted and tested in future research syntheses.Electronic supplementary materialThe online version of this article (doi:10.1186/s13643-015-0125-0) contains supplementary material, which is available to authorized users.
Highlights
Grey literature is an important source of information for large-scale review syntheses
The search strategies for identifying and screening publications for inclusion in the case study review were found to be manageable, comprehensive, and intuitive when applied in practice
The search strategy we developed and tested is amenable to adaptation to identify other types of grey literature from other disciplines and answering a wide range of research questions
Summary
Grey literature is an important source of information for large-scale review syntheses. The ‘Luxembourg definition’ offers a widely accepted description for grey literature as ‘that which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers, i.e., where publishing is not the primary activity of the producing body’ [1]. These documents are not formally published in academic sources (i.e. books or journals) and include items such as reports, theses, conference proceedings, newspapers, fact sheets, websites, and policy documents. Grey literature documents can serve as valuable resources for practitioners and decision-makers across disciplines, since these documents often contain policy- and research-relevant information (e.g. clinical practice guidelines, research reports, program evaluation studies, legislation) from authoritative sources and tend to be widely accessible (i.e. subscriptions are not required as may be the case with the peer-reviewed scholarly literature)
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