This is an evidence base pyramid. It is often used as a reference to illustrate evidence based literature. Before starting a literature search, use this illustration as a reference on where to begin. Beginning at the top will give you the highest quality of literature.
Filter information is information that has been filtered to include studies that are of the highest quality. These resources have been evaluated for their quality and are recommended for practice As you ascend the pyramid you will see that amount of studies begin to decrease, but the quality of the studies increase. These studies include:
Unfiltered information is made up of primary or original research studies. This tier has information that covers a much broader range of clinical issues, however you may not find studies that are of the highest quality. These studies include: