Grey literature

The term 'grey literature' refers to a wide range of information which is not formally or commercially published. 

Grey literature is usually produced by government departments and agencies, local authorities, academic institutions, professional organisations, research groups, think tanks, charities and comes from many other sources.

Examples of grey literature include the following types of materials: reports, policies, briefings, pamphlets, conference proceedings, clinical trial registries, doctoral theses, interviews, social media outputs (such as blogs, podcasts, etc.).

• To find current and emerging research: Formally published research can take time going through lengthy peer review and editorial processes unlike materials such as trial registers, pre-prints and working papers which provide details of ongoing research. Upcoming research can also be found in conference proceedings as conferences are often where new research is first announced.
• To broaden your research: Innovations from the private sector, policy from government and engagement with the public as patients or beneficiaries of research will not generally be published in academic journals and books. Policy documents, industry papers and social media will help you keep up to date with social and economic updates in your field. 
• To mitigate against 'publication bias': Studies showing positive research results are much more likely to be published in journals. A search for grey literature will help to ensure that all relevant results, even if negative, are located.
• To find viewpoints of individuals, such as patients and consumers. 
• To find more in depth or practical coverage of topics: Research results may be more detailed in primary source reports and documents. 
• To access unpublished conference proceedings and research. 

Challenges of grey literature

• Grey literature can be regarded as less prestigious and less organised than published literature as is not always peer reviewed or fully edited.
• It may include raw data and findings that are incomplete. 
• Grey literature can be produced in various formats and be written in lots of different styles, therefore care must be taken when extracting complex data and information.
• Papers, briefing documents and fact sheets, etc. from organisations might not always be unbiased. 

If you would like to explore further, below are a few articles which give examples of the debate about and the use of grey literature in research. 

• Are electronic theses and dissertations (still) grey literature in the digital age? A FAIR debate 
• Grey literature: an important resource in systematic reviews
• Grey literature: its emerging importance
• Unlocking grey literature in the social sciences