hirsch;159062 Wrote: > > DBX is useful for helping to interpret a positive result. Nothing > more. *The absence of a positive result does not imply a negative > result.* This cannot be overemphasized. The problem with DBX in audio > is that people don't know how to interpret the results.
I really don't see what you're getting at. Why do we need any help interpreting negative results? If you can't hear a difference in a non-blind test most people would have little difficulty in deciding what that means - it means that there any difference is too small to be perceptible to them, and therefore they're not going to blow $1000 on that component. The *only* difficulty, and the source of all the arguments on this and many other forums, is in interpreting positive results from non-blind tests. Suppose you think there might be a perceptible difference between two components. So you do a blind ABX test and try to distinguish between the two components. You identify X as A or B correctly n out of 10 times, say. Now, in statistics 101 you learned about "rejecting the null hypothesis." That means you start from the hypothesis that there is no difference, and you see with what confidence you can reject it given the results of your test. So you simply need to ask, what is the probability p that you would randomly happen to be correct n out of 10 times if there is, in fact, no difference. Then with confidence 1-p you can reject the null hypothesis. Usually we require 1-p > .95 (p < .05) to say the result is significant, although of course that's a convention. In the example above you'd need to identify correctly 8/10 times to reject the null hypothesis with 94.5% confidence, so that would be almost but not quite at the conventional level of significance (I'm assuming a result of 8 or more *wrong* answers would not be regarded as a positive result - otherwise it's only 89% confidence). Now, if instead you are correct, say, 5/10 times, does that mean you can conclude there is no difference at all? Of course not - it might simply mean the difference isn't audible to you... which is exactly what you wanted to know in the first place. -- opaqueice ------------------------------------------------------------------------ opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=29912 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
