Searching for Grey Literature
Medical Information Specialist
Cochrane Schizophrenia Group
Presentation at: Information Retrieval Topics: Grey Literature Search [Webinar]; September 9, 2015;
Systematic Review Solutions Ltd. China, Malaysia and UK
Permanent URL: http://dx.doi.org/10.13140/RG.2.1.3322.6722
What is grey literature?
• Cochrane Handbook:
– “literature that is not formally published in sources such
as books or journal articles”
– “Type of information or research output produced by
organisations, outside of commercial or academic
publishing and distribution channels”
• The Fourth International Conference on Grey Literature
– “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
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– Usually NOT published by a commercial publisher
– Usually NOT distributed widely
– Usually NOT controlled/indexed
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Why do we call it “grey”?
• It is not as invisible as ‘darkness’: e.g. thoughts!
• Here it stands
• It is not as visible as ‘light’: e.g. publications
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Advantages: why is it important?
• Sometimes the info are only available as grey literature not any other
format (e.g. a thesis that never get published as a paper)
• Usually high quality (e.g. PhD dissertation)
• Usually free
• Usually more detailed info (compare thesis versus journal paper
published based on thesis)
• Usually with quick output (again compare thesis versus journal paper
and its process of peer-review, edit, formatting, indexing, etc.)
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Disadvantages: what are limitations?
– No comprehensive database
– No indexing or bibliographic control/record/citation
– No serious collecting body
– No estimation of size of grey literature
– Public or private?
– Copyrighted or restricted with permission?
– Permanent access or limited to time/place?
• Quality evaluation
– Content quality: Peer-reviewed or not?
– Physical quality: Formatting and layout quality?
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What are types of grey literature?
• Conference abstracts
• Dissertations, and theses (academic reports)
• Reports (proposals/protocols, progress reports,
final reports, annual reports, etc.)
• Technical specifications and standards
• Lecture presentations and notes
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Where to find them: Databases
– Open Grey (Europe-focused)
– British Library (International-focused)
– Healthcare Management Information Consortium
(HMIC) via Ovid SP (UK-focused)
– National Technical Information Service (NTIS) (Us-
– PsycEXTRA (psychology-focused)
– Repositories: OpenDOAR - the Directory of Open
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Where to find them: Dissertations and Theses
– ProQuest’s Dissertations and Theses (International focus)
– British Library’s EThOS Service
– Open Access Theses and Dissertations Database
– DART-Europe E-theses Portal (DEEP)
– CINAHL (subject focus on nursing theses)
– www.theses.com/ (UK-focused)
– www.dissonline.de/ (Germany-focused)
– Networked Digital Library of Theses and Dissertations (NDLTD)
– Theses Canada Portal
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Where to find them: Conference Proceedings
– Web of Science
• Conference Proceedings Citation Index- Science (CPCI-S)
• Conference Proceedings Citation Index- Social Science &
Humanities (CPCI-SSH) --1990-present
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Where to find them: Clinical Trials
– WHO ICTRP
– CENTRAL: Cochrane Central Register of Clinical Trials
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Choice in hand!
Good for scoping general grey lit search
Not reliable results during time
Only first 1000 hits could be viewed
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What to do now?
Source: Alex E. Proimos - http://www.flickr.com/photos/proimos/4199675334/
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Why do you need to know about this?
• If you do any kind of research you have to do a review:
– Literature reviews (for research, thesis, or project)
– Scoping review (to know the scope of a topic)
– Systematic review (to build a reliable body of knowledge
through research synthesis in a specific topic)
• Preventing “publication bias”: “Published trials showed an overall
greater treatment effect than grey trials” and “published trials had
more participants on average” (Hopewell 2007)
• Time to search grey: “The median time spent searching all
resources was 471 minutes, and of those a median of 85 minutes
were spent searching grey literature” (Saleh 2014)
– In topics with very little literature, go ‘grey’!
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When you are doing any kind of review…
• List the potential sources for grey literature
• Ask experts about other possible grey literature
• Search for grey literature and use them
• Cite them as a usual reference in your work
• Check the permission to use if you use a table,
picture, figure or major part of a work
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*Document your search for grey literature*
• Your search methods are part of your research
methods so they should be reproducible
– Where did you search?
– When did you search?
– What were the search strategies?
– How many results did you find?
– Who did the search?
• If you provide this info, anyone can re-
run/repeat your search!
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If you are interested in this topic:
• Finding the Hard to Finds: Searching for Grey Literature
• Grey lit 101: Shining a White Light on Grey Literature
• Grey lit 102: Advanced Search Strategies for Grey Literature
• Grey lit 103 Standing Out in a Sea of Grey Literature A Producer’s (Librarian) Perspective
• Finding Grey Literature Evidence and Assessing for Outcome and Analysis Reporting Biases
When Comparing Medical Interventions: AHRQ and the Effective Health Care Program
• Grey Matters: a practical search tool for evidence-based medicine
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Thanks for Your Attention
Ask a Question, Please!
• Feel free to contact me at
– farhadshokraneh [at] gmail.com
– farhad.shokraneh [at] nottingham.ac.uk
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