You have a sample size of one, and no control group. The patient dies. Are either of the drugs safe individually? Can&#x27;t tell. Maybe one caused death and the other was fine. Maybe the two interacted in the human body somehow.<p>Okay, now consider the scenario where the patient lives. Are either of the drugs safe individually? Can&#x27;t tell. Again, maybe the two interacted in the human body in such a way that a potentially lethal treatment was rendered ineffective at curing or killing.