The term grey literature is used to describe a wide range of different information that is produced outside of traditional publishing and distribution channels, and which is often not well represented in indexing databases.
A widely accepted definition in the scholarly community for grey literature is
"information produced on all levels of government, academia, business and industry in electronic and print formats not controlled by commercial publishing" ie. where publishing is not the primary activity of the producing body."
From: Third International Conference on Grey Literature in 1997 (ICGL Luxembourg definition, 1997 - Expanded in New York, 2004).
When conducting a systematic review it is important to include literature that has not formally been published in sources as it helps to prevent publication bias. An exhaustive literature search, especially one that leads to a systematic review, needs to include searches in gray literature, to overcome, or at least minimize, “publication bias” or “reporting bias”. Searching grey literature is supported/mandated by the Cochrane Collaboration, the Campbell Collaboration, JBI and the Institute of Medicine (U.S.)
Pros & Cons of Grey Literature: Uniqueness and Currency VS. Quality and Longevity
Grey Literature can be a very important research resource.
You should be aware of the need to assess and capture potentially useful resources
A wide, and growing, range of material can be considered as grey literature. For example, clinical trial information is primarily of interest to health and medical research. You should consider which types of information you are interested in before you begin searching as this will help you target and frame your online searching.
Examples include:
Blogs | Newsletters |
Clinical Trials | Pamphlets |
Company Information | Patents |
Conference Paper or Proceedings | Policy Statements |
Data sets | Pre Print Articles |
Discussion Forums | Press Releases |
Dissertations and Theses | Research Reports |
Email Discussion Lists | Statistical Reports |
Government Documents and Reports | Survey Results |
Interviews | Tweets |
Professional Societies or Organizations | Wikis |
Working Papers | |
White paper |
This is only a small sample of Grey Literature sites
Medical Education
AAMC: MedEd Portal is a MEDLINE-indexed, open-access journal of teaching and learning resources in the health professions published by the Association of American Medical Colleges (AAMC). MedEdPORTAL publications are stand-alone, complete teaching or learning modules that have been implemented and evaluated with physician trainees or practitioners.
Foundations
Reports and Research
Clinical Trials
Health Statistics
Wide variety of health-related statistics, including FastStats for quick summary data.
Descriptions of Federal datasets (metadata), information about how to access the datasets, and tools that leverage government datasets.
Datasets, tools & applications using data about health and health care gathered from US Federal government agencies. Social-science data and statistics from a variety of sources.
Interface for data from Census 2010 and 2000 and the 2010 American Community Survey. Tables and maps for U.S states, counties, cities, towns, by race, ethnic, ancestry, or tribal groups.
Health data tools and statistics.
US Vital Statistics/ Health & Disease
Women’s Health
Youth and Aging in the US
US Health Services
International Statistics