The evidence pyramid can help us understand the strengths and limitations to different types of studies. While the pyramid is hierarchical in nature, with systematic and meta-analysis reviews at the top and animal studies at the bottom, this does not mean that all animal studies are bad or that all systematic reviews are good. Critical appraisal and evaluation are crucial to the process of finding good evidence for your research questions.
Consult the table below for a quick explanation of advantages and disadvantages of the various study types:
Table courtesy of Evidence Based Practice for Health Sciences Librarians, an Introductory Workshop. MUSC Libraries.