The aim of this presentation is to demonstrate the scientific approach for critical appraisal of the literature highlighting the weakness and strength of the following research designs;

• 1.

  Meta-analyses

• 2.

  Systematic reviews

• 3.

  Randomized clinical trials

• 4.

  Cohort studies

• 5.

  Case control studies

• 6.

  Cross sectional studies

• 7.

  Case series

• 8.

  Case reports

• 9.

  Expert opinion

The following parameters should be considered to identify the strongest possible evidence in the literature:

• 1.

  Focused aims

• 2.

  Rigorous scientific methodology (hypothesis, sample size, bias minimized)

• 3.

  Robust analysis of the results

• 4.

  Logical conclusion