<prompt> Evidence based ortho research is based on the following studies:CohortCross SectionalSystematic studiesRCT  <response>: Evidence-based medicine pyramid. The levels of evidence are appropriately represented by a pyramid as each level, from bottom to top, reflects the quality of research designs increasing and quantity decreasing of each study design in the body of published literature. For example, systematic reviews are higher quality and more labor intensive to conduct, so there is a lower quantity published. 