On to placebo. In any serious controlled trial of a medical drug, there are two groups. One group gets the drug; the other gets a sugar pill. The reason for this practice has been obscured in modern times. Actually, it is done because a certain percentage of people (around 20%) will get better no matter what you give them. Therefore, the drug has to perform significantly better than the placebo.
However, we need to return to the medical origin of the placebo.
This is it: a country doctor, faced with a patient who was a hypochondriac, would hand him a sugar pill. The patient would take it and then feel better.
But…you see, the patient believed he was getting effective medicine. That’s what caused him to recover.
In a controlled trial, this is not the case. The patient knows, beforehand, that he will get EITHER the medicine or a placebo. This setting doesn’t provoke the same belief. It’s different. It’s weaker.
Therefore, one can expect that the “cure rate” in the placebo group will be lower than the normal 20%. And, as a result, the actual drug will only need to meet a lower standard of success, relative to the results obtained by the placebo.
Bottom line? A medical drug can test out with fewer positive outcomes to be deemed effective. Unless someone decides that the placebo group performed in an unexpected manner—but who cares about that when the goal is to establish that the drug is a winner?