I&#x27;m not entirely sure about that.  Some trial designs do indeed have an arm of &quot;no intervention&quot; or &quot;usual care&quot; or &quot;waiting&quot;.  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 - - &quot;pragmatic&quot;  trials in particular don&#x27;t tend to follow typical masked, randomised, placebo-controlled designs.