I'm not entirely sure about that. Some trial designs do indeed have an arm of "no intervention" or "usual care" or "waiting". Sometimes these groups may be gi

I'm not entirely sure about that. Some trial designs do indeed have an arm of "no intervention" or "usual care" or "waiting". Sometimes these groups may be given the active therapy after the trial ends, since withholding a potentially effective and efficacious therapy may be considered unethical. There are many trial designs, not all of them are lab-based - - "pragmatic" trials in particular don't tend to follow typical masked, randomised, placebo-controlled designs.