手法を比較

	ブール演算子	グレィ・リテラチャー・サーチ（非商業的文献検索）	体系的な検索戦略
分野	研究スキル	研究スキル	研究スキル
系統	Process / pipeline	Process / pipeline	Process / pipeline
提唱年	1847 (Boolean algebra); 1960s (database applications)	1990s (formalized in systematic review guidelines)	1990s (formalized in Cochrane methodology)
提唱者	George Boole and IT information retrieval practitioners	Information specialists and systematic review methodologists (Cochrane Collaboration, Health Technology Assessment)	Cochrane Collaboration and systematic review methodologists
種類	Tool	Tool	Framework
原典	Wilkinson, M. D., Sansone, S. A., Vandervalk, B., & Rocca-Serra, P. (2011). Evaluating information retrieval systems: a guide for researchers. Expert Review of Molecular Diagnostics, 11(2), 181–190.	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.
別名	Boolean logic, Boolean search, AND OR NOT	grey literature, gray literature, unpublished literature	search protocol, systematic search, comprehensive search strategy
関連	2	3	3
概要	Boolean search operators are logical functions—AND, OR, NOT, and parentheses—used to combine and filter search terms in bibliographic databases, library catalogs, and search engines. Named after mathematician George Boole (1815–1864), Boolean logic has been applied to information retrieval since the 1960s. These operators allow researchers to construct complex, precise searches that retrieve only articles meeting specific combinations of criteria, dramatically improving search efficiency and reducing irrelevant results.	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.