Before revision: Natural history groups The practice of using an additional natural history group as the trial's so-called "third arm" has emerged; and trials are conducted using three randomly selected, equally matched trial groups, Reilly p.28 wrote: "... it is necessary to remember the adjective ‘random’ [in the term ‘random sample’ ] should apply to the method of drawing the sample and not to the sample itself.".
After revision: Natural history groups The practice of using an additional natural history group as the trial's so-called "third arm" has emerged; and trials are conducted using three randomly selected, equally matched trial groups, Reilly p.28 wrote: "... it is necessary to remember the adjective 'random' [in the term 'random sample' ] should apply to the method of drawing the sample and not to the sample itself.".