Methoden vergelijken

	Grijze literatuur zoeken	Systematische zoekstrategie
Vakgebied	Onderzoeksvaardigheden	Onderzoeksvaardigheden
Familie	Process / pipeline	Process / pipeline
Jaar van ontstaan	1990s (formalized in systematic review guidelines)	1990s (formalized in Cochrane methodology)
Grondlegger	Information specialists and systematic review methodologists (Cochrane Collaboration, Health Technology Assessment)	Cochrane Collaboration and systematic review methodologists
Type	Tool	Framework
Oorspronkelijke bron	Rothstein, H. R., & Hopewell, S. (2009). Grey literature. In J. P. Higgins & S. Green (Eds.), Cochrane handbook for systematic reviews of interventions (Version 5.0.2, Chapter 13). The Cochrane Collaboration.	Moher, D., Liberati, A., Tetzlaff, J., & Altman, D. G. (2009). Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA statement. PLoS Medicine, 6(7), e1000097.
Aliassen	grey literature, gray literature, unpublished literature	search protocol, systematic search, comprehensive search strategy
Verwant	3	3
Samenvatting	Grey literature comprises documents and data not published through conventional commercial channels—including theses, government reports, clinical trial registries, conference abstracts, organizational policy documents, and working papers. Unlike journal articles, grey literature is not indexed in MEDLINE or Scopus and often lacks peer review. However, it is crucial for systematic reviews because it may contain null or negative findings that are less likely to be published (publication bias). Systematic grey literature searching is now a standard component of evidence synthesis and is recommended by the Cochrane Collaboration, PRISMA, and other methodological guidelines.	A systematic search strategy is a comprehensive, transparent protocol for retrieving all relevant literature addressing a well-defined research question. Developed by the Cochrane Collaboration and formalized in guidelines like PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses), systematic search strategies are essential for conducting unbiased literature reviews, systematic reviews, and meta-analyses. Unlike ad hoc searches (searching Google Scholar or PubMed without a protocol), systematic searches document every step—which databases were searched, what search terms were used, how many results were retrieved, and what inclusion/exclusion criteria were applied—enabling other researchers to reproduce the search and verify that no relevant studies were missed.