Original primary research studies are the basis for the other types of evidence listed in this guide. There are many sources but biomedical literature databases such as PubMed, Embase, and CINAHL are the most often used.
Preappraised sources have gone through a rigorous filtering process to assess their quality and currency. These information sources are highly curated and include the summaries and synopses resources found on this guide.
Non-appraised sources may also include evidence based material, but remember that they may be outdated or of lower quality. An example of non-appraised sources are biomedical databases like PubMed. They do not critically evaluate what is in the database beyond if it is published in a journal chosen to be included in the database. Additionally, items are not removed due to date of publication or other factors.