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This guide provides links to information resources useful to students enrolled in psychology courses, and students pursuing research projects in other courses that are on topics related to psychology

Levels of Confidence - the Hierarchy of Scientific Evidence

In any scientific field, it's important to provide evidence to support your statements.  But not all evidence is equally reliable. Generally scientific research will involve carefully designed studies, with randomized controlled trials being one of the strongest types of research - while case reports and animal trials are considered much less strong (although they are still scientific).  Click on the link below to find out more.


Diagram of a pyramid showing different levels of evidence in order of reliability, from the weakest at the bottom to the strongest at the top. A circle to the right contains a list of items that is labeled "not scientific evidence". A full description of the hierarchy is available on the linked page.

Citation Styles

Always ask your instructor what citation style should be used for research projects. See below for links to helpful resources.


Cathy Cox's picture
Cathy Cox
Cathy Cox
Library Director
College of the Redwoods
7351 Tompkins Hill Rd.
Eureka, CA 95501