A trial with an experimental group who will be given a novel drug vs a control group given placebo

Single-arm trial, where all subjects are enrolled in the experimental group given a novel drug for a condition with no standard known treatment

A trial with a single placebo group, for a condition where there is a proven effective standard treatment

A trial with a placebo alone group when there is evidence that the harms of an existing standard standard treatment exceed the benefits of the treatment

A trial with a single placebo group, for a condition with no proven effective treatment