Table 1.4 Levels of Evidence

Level	Research Design	Description
Level 1a	Randomized Controlled Trial (RCT)	More than 1 RCT with PEDro score ≥6. Includes within subjects comparison with randomized conditions and crossover designs.
Level 1b	RCT	1 RCT with PEDro ≥6.
Level 2	RCT	RCT, PEDro <6.
	PCT	Prospective controlled trial (not randomized).
	Cohort	Prospective longitudinal study using at least two similar groups with one exposed to a particular condition.
Level 3	Case Control	A retrospective study comparing conditions including historical controls.
Level 4	Pre-Post test	A prospective trial with a baseline measure, intervention, and a post- test using a single group of subjects.
	Post-test	A prospective intervention study using a post intervention measure only (no pre-test or baseline measurement) with one or more groups
	Case Series	A retrospective study usually collecting variables from a chart review.
Level 5	Observational Study	Using cross sectional analysis to interpret relations
	Clinical Consensus	Expert opinion without explicit critical appraisal, or based on physiology, biomechanics or “first principles”.
	Case Reports	Pre-post or case series involving one subject.