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Engineering Systems, Supply Chain Management, Professional Engineering: Grey literature

What is Grey Literature?

"Grey literature stands for manifold document types produced on all levels of government, academia, business and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by libraries and institutional repositories, but not controlled by commercial publishers, i.e.where publishing is not the primary activity of the producing body.” (International Conference on Grey Literature, 2010).

It is sometimes referred to as ephemeral, fringe, gray or fugitive literature.

Examples and characteristics

Not peer-reviewed

Lacks editorial polish

Not conventionally published

Raw data

Incomplete work

Unorganised research

Less prestigious

May be made publically available or distributed privately

►Master’s dissertations & doctoral theses
►Conference proceedings
►White papers
►Lecture notes
►Technical reports
►Institutional repositories
... more examples ...

Why is grey literature important?

►Relevant alternative perspective on topic
►Can alter the findings of reviews
►Covers emerging research areas
►Can provide more up-to-date evidence than traditionally published sources
►Timeliness:  available 12-18 months before official publication
►Expert opinion encourages use of grey literature sources for realist reviews

Who produces grey literature?

Different bodies produce grey literature, including the University and you.  It is produced by the medical sciences, business and social sciences, all levels of government and industry in print and electronic formats.  Here are some additional examples:

  • Think tanks
  • Research groups
  • Scholarly societies and associations
  • Non-profit organisations
  • Universities
  • You

Grey literature awareness

Looking for unpublished material is a good way to counteract publication bias and include a broader scope of the literature. However, grey literature has not been through any peer review process and needs to be carefully evaluated. Flinders University have created the AACOD checklist to enable evaluation and critical appraisal of grey literature:

A Authority

A Accuracy

C Coverage

O Objectivity

D Date

S Significance

Not all grey literature will have a named author (or authors). If it does, consider whether the author or authors are knowledgeable in the field and whether they have any affiliations that might bias their views. If no authors are named, consider closely the source that produced the report. Source information should be obvious and easy to locate.  It should be clear where data and other types of information came from, how it was analysed and how the final report was compiled; transparency of method.  The date a report was issued should be easy to find. If a report is older, try to find a more recent version or an update; currency.

Benefits of including grey literature in the review process include:

  • broader scope of literature for more comprehensive view on a topic
  • primary means of distributing scientific and technical data
  • grey literature can describe neutral or negative results as opposed to favoring positive results (counteracting publication bias)
  • research results can be more detailed in primary source data and reports  
  • some conference proceedings and research is never officially published 
  • research generated in less developed countries where researchers cannot always rely on commercial publishing channels 
  • advances in hard and medical sciences move quickly and require quick publishing process 
  • faster access to cutting-edge material

It can be tricky to find grey literature because traditionally there were no central sources such as libraries or databases where it would be collected.  It is not systematically described, organised or indexed.  Neither has it gone through a formal peer-reviewing process and it has been argued that for this reason grey literature should not be included in systematic reviews.

It can be harder and more time-consuming to identify relevance in the title and abstract stage of a review as citation information or abstracts may not exist and it does not conform to a specified format (abstract, methods, results, discussion) as peer-reviewed literature does.

Where to find it ...

Examples of where to search for grey literature:

Google Scholar advanced search – academic material

Google advanced search  - general search

  • Use exact phrases, don’t use truncation
  • Limit - in the title of the article
  • Specify the domains – gov, ac, edu, org
  • AND is default and all typed keywords must be mentioned
  • OR to link synonyms