Grey literature is “information produced by all levels of government, academics, business and industry in electronic and print formats not controlled by commercial publishing”, (GreyNet) and includes materials such as theses and dissertations, working papers, policy statements, technical reports and government documents.
Why include grey literature in your review?
For completeness. Whilst it is rarely peer-reviewed, grey literature is often a good source of the most up-to-date information on a topic. Including it reduces publication bias and it may be the only source of some data.
The AACODS checklist is a useful method to quickly evaluate grey literature.
Authority - who is the author?
Accuracy - does it have a clearly stated aim and methodology? Have these been adhered to? Is it supported by credible sources?
Coverage - are any limits clearly stated?
Objectivity - does the work seem to be balanced in presentation?
Date - is it current? No easily discernible date is a strong concern.
Significance - does it enrich or add something to your review?
Tyndall, J. AACODS Checklist. Flinders University, 2010.