Table 1. Classification of Articles Based on Obtained Evidence.

Level	Type of Evidence
I	Evidence obtained from meta-analysis of multiple, well-designed, controlled studies. Randomized trials with low false-positive and low false-negative errors (high power).
II	Evidence obtained from at least one well-designed experimental study. Randomized trials with high false positive and/or negative errors (low power).
III	Evidence obtained from well-designed, quasi-experimental studies such as non-randomized, controlled single group, pre-post, cohort, time or matched case-control series.
IV	Evidence from well-designed, non-experimental studies such as comparative and correlational descriptive and case studies.
V	Evidence from case reports and clinical examples.