Table 1: AASM (American Academy of Sleep Medicine) Classification of Evidence (Based on Sackett system, (6) the criteria for grading evidence level of each study) Randomized well-designed trials with low alpha and
beta error (Grade I) Randomized trials with high alpha and
beta error (Grade II) Non-randomized concurrently controlled studies (Grade III) Non-randomized historically controlled studies (Grade IV) Case series (Grade V) (Alpha (Type I error) refers to the probability that the null hypothesis is rejected when in fact it is true (generally acceptable at 5% or less, or p<0.05).