Proof of placebo effect ?

[DrJeff]

Seems to me that by adopting the coin toss analogy to this situation you are assuming as a given that the hearing ability, training and experience of all the participants are equal.

Perhaps so, but let's assume for the sake of your argument that we will use only those who describe themselves as "audiophiles" in our next hypothetical test.

I don't know statistics, but I know enough to recognize the difference.

As for medical trials with large number of participants and trials, they are attempting to determine the effectiveness of a particular medicine on a large enough segment of the populace as to justify its use. Whether it works or not (it either does or doesn't) on a single individual within the broad group is meaningless, as they are concerned with percentage of effectiveness as to the entire group. They have to do it this way, as they can never be sure that a test subject who received real medicine and appears to have been cured was cured as a result of the medicine or a result of the placebo effect. They can only compare the overall results of the non-placebo group with that of the placebo group.

I agree with that statement entirely.

I submit that in audio DBTs you don't have that situation. If the test is conducted properly, the pacebo effect, or the power of suggestion, or the ABE's or whatever you want to call influences that are not actual audible differences, should all be controlled out of the test, with the only thing left to test being actual audible differences. If one person can identify correctly 11 out of 15 times, there's no possible chance that placebo or ABEs could be at work, again assuming the test is properly conducted, so his correct guesses either have to be the result of chance (a very low possibility) or due to actual sonic differences he was able to detect; whereas, as I said, if the medicine seems to work on a single individual there still is no way of determinining if it was due to placebo or the real thing. This is a significant difference between audio DBTs and medical DBTs.

I agree that you can have a DBT test that very effectively minimizes placebo effect and other factors, leaving only one variable for the subject to judge. However, I think that a person guessing 11 out of 15 ONCE is just as likely as any other scenario. In irder to make the test valid, you would want to perform multiple runs of the same test. For example, can this person get it right 11 out of 15 times per run, for 5 consecutive runs. Of course the cable selection would be random so no pattern existed in switching. If his correct guesses for all 5 runs were in the 10 to 15 range, then I am convinced he can perceive a diffeence. However, if his guesses came up something like 11, 4, 10, 7, 5 then I would have to say he cannot hear a difference.

It can get very confusing, so I would leave it to people with more time and desire, but I believe a proper test could be conducted, I just haven't seen it yet.....