Steven Sullivan wrote in message news:UqnVa.4003$Oz4.1480@rwcrnsc54...
Thomas A wrote:
Steven Sullivan wrote in message news:d_XUa.142496$GL4.36308@rwcrnsc53...
Thomas A wrote:
Is there any published DBT of amps, CD players or cables where the
number of trials are greater than 500?

If there difference is miniscule there is likely that many "guesses"
are wrong and would require many trials to reveal any subtle
difference?

There are published tests where people claimed they could hear the
difference sighted , but when they were 'blinded' they could not.
In this case the argument that 500 trials are needed would seem
to be weak.

Yes, that's for sure. But how are scientific tests of just noticable
difference set up? A difference, when very small, could introduce more
incorrect answers from the test subjects. Thus I think the question is
interesting.

However, a real and miniscule difference would certainly be
discerned more reliably if there was specific training to hear it
beforehand.

Yes, but still, if the difference is real and miniscule it could
introduce incorrect answers even if there is specific training
beforehand. If there would be an all or nothing thing, then the result
would always be 100% correct (difference) or 50% (no difference).
What if the answers are 60% correct?

What level of certitude are you looking for? Scientists use
statistical tools to calculate probabilities of different
kinds of error in such cases.

Well confidence limits of 95% or 99% are usually applied. The power of
the test is however important when you approach the audible limit.
Also, in sample sizes 200 you need not use correction for continuity
in the statistical calculation. I am not sure, but I think this
correction applies in this case when sample sizes are 25-200. Below
25, this correction is not sufficient.