When reading the report of a clinical study in a medical journal, the typical question an overly busy clinician-reader asks is the following: do the results convince me and are they valid? In the era of evidence based medicine, the randomised clinical trial has become the reference-standard of all designs, when assessing the efficacy of a certain treatment or predefined diagnostic handling. This is because the comparison is based on random allocation of patients to the experimental arm or control arm of the trial, thereby preventing confounding by indication.
