While evidence syntheses require close review and comprehensive perusal of the black and white literature provided in scholarly publications, authors are also encouraged and expected to review grey literature sources.
Research shows that the trends in literature citations are becoming more and more inclusive of grey literature:
As authors aim to be more comprehensive in their research, it is increasingly important to consider all available streams of literature.
Several books and standards encourage or require authors to review grey literature when conducting evidence syntheses. Because relevant research may have been conducted but not published in traditional formats, researchers should consider a strategy to include reviewing grey literature.
The following table, from Doing a Systematic Review: A Student's Guide, 2nd Edition, provides insight on the benefits (and limitations) in utilizing grey literature in an evidence synthesis (Boland, Cherry, & Dickson, p. 65).
|Published Literature||Grey Literature|