HSS - Health Systems Science: Application of HSS

The Evidence-Based Pyramid represents the types of sources you will find.  At the top you will find your pre-appraised, filtered secondary sources derived from the trials and studies done in the field.  Toward the middle you'll find the primary sources; the controlled trials and observational studies.  And, at the bottom you will find the tertiary summary sources like textbooks.

The information at the top of the pyramid may be harder to find but it is generally the "best" type of evidence to look at while researching.  The information at the bottom of the pyramid is more plentiful, but you need to be selective about what you include.

The type of evidence you use depends on the type of research you are conducting.