Table 1.

Validity measures

Major criteria
1. Was the assignment of patients to treatments randomized?
2. Were all patients who entered the trial accounted for at its conclusion?
3. Were the patients analyzed in the groups to which they were randomized?
Minor criteria
1. Were patients and clinicians kept "blind" to which treatment was being received?
2. Aside from the experimental treatment, were the groups treated equally?
3. Were the groups similar at the start of the trial?