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Grey Literature in the Health Sciences: Overview

Guide to locating and evaluating grey literature (or gray literature) in the health sciences.

What is Grey Literature?

Grey literature is created by researchers and practitioners in various fields, but is not controlled by commercial publishing. The groups that produce grey literature may be government, industry, advocacy or other organizations that disseminate information in the form of reports or working papers rather than by publishing scholarly articles in commercial journals.

Grey literature can be found in the form of:

  • reports
  • conference papers, posters or proceedings
  • policy documents
  • preprints
  • data sets
  • standards
  • translations
  • clinical trial data
  • factsheets
  • dissertations
  • committee reports
  • and more

More often than not, grey literature is not indexed in databases and so can be a puzzle to find. Locating grey literature can be a very different process than locating scholarly articles. For more tips on finding grey literature in the health sciences, click here.

Why is Grey Literature Important?

In the health sciences, grey literature is vital for developing a more complete view of research on a particular topic and for producing systematic reviews and other rigorous approaches to evidence synthesis. Grey literature can be a good source for data, statistics and for very recent research results. Because there's no publisher-enforced limitation on length, these reports can be much more detailed than the journal literature. And they can help to offset issues related to publication bias such as:

  • publication lag  Results of studies may appear in grey literature, such as conference proceedings, a year or more before they appear in a peer-reviewed publications.
  • positive result bias  Study results that show a negative or no effect are published in scholarly journals less often than those that show a positive effect. Those negative results may be found by reviewing the grey literature.

Grey literature is particularly important in the area of health policy where health technology assessments, economic evaluations, health systems impact assessments and comparative effectiveness research are of special interest.

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