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:
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.
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:
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.