General Asylum

There are two cases you need to consider:

70.16.99.162

In Reply to: RE: You're obfuscating. Or maybe not. posted by andy19191 on March 28, 2008 at 14:11:22

>>However, you can also test the hypothesis: are the results drawn from a population that cannot hear a difference (i.e. a random population)? If the answer to that is yes then you have shown to a given level of confidence that a sound cannot be perceived.<<

1. The test is population based. Then what you write above is true as a sort of population average--or, to put it another way, it's completely true IF you assume a uniform population. Add individual variation and you get a very different conclusion: If one individual, or a subgroup, can hear the difference, then it exists (but usually that's not what's being tested). Even in clinical trials of pharmaceuticals that aren't approved, some people always benefit.

2. If the test is administered to an individual, so that there's truly no intra-population variation, there's still the issue of sensitivity, which falls with the test duration (correlated with fatigue, apparently). In this case my earlier statement applies: that a null result fails to establish perception but does NOT rule out the possibility that it might be perceived (so you can't prove that it's NOT real).

In either case the conclusion is the same: you cannot use an ABX test to rigorously conclude that there's no effect on the sound (thus on the possibility of perception). ABX testing can be used to establish an effect (so your first claim in the above message is true) but cannot be used to rigorously reject a hypothesis...so the second claim in your above message is false. It's an important distinction.

Since we started off talking about cables--and since you seem to be okay with less-than-perfectly-rigorous results--you should check out the recent commentary by Lee Gomes of the Wall Street Journal, a skeptic who was impressed that (in a blind, but not double-blind, test) Stereophile editor John Atkinson and columnist Michael Fremer were able to easily distinguish differences between cheap and expensive cables. Since it's not double blind (the methodology was single-trial, "A-B Forced Choice"), it's not conclusive (as JA has said), but it's very suggestive that something real is going on.

Jim

Follow Ups:

RE: There are two cases you need to consider: - andy19191 06:42:22 03/30/08 (1)
- RE: There are two cases you need to consider: - Jim Austin 12:47:29 03/30/08 (0)

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