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Old 10th September 2012, 08:37 AM   #27481
SY is offline SY  United States
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Quote:
Originally Posted by fas42 View Post
A bit like the nature of the universe: at any point in time what's called science always understands how everything works, until some annoying individual or group of people drags some irritatingly contradictory evidence out of the woodwork.
Absolutely true (other than the "understand everything" hyperbole). Of course, there's that annoying "evidence" thing...
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Old 10th September 2012, 09:20 AM   #27482
Jakob2 is offline Jakob2  Germany
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It is hard to understand that one can talk about validation and refuses at the same time to accept that any test has to be validated too.

Controlled listening tests are part of the scientific tool box and the rules are strict; a test has to be objective, valid and reliable.

An ABX uses a standard protocol but relies on a human detector (aka listener) and some sort of switching device (if used for amplifiers for example).

Without using positive and negative controls it is simply impossible to fulfill the scientific requirements (means to show that it is valid).

Without that the result of any test is only "null hypothesis could not be rejected" or "null hypothesis could be rejected" but no further conclusions about the reasons for these results can be drawn, which means that the test is quite useless.

Last edited by Jakob2; 10th September 2012 at 09:23 AM.
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Old 10th September 2012, 09:34 AM   #27483
SY is offline SY  United States
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Originally Posted by Jakob2 View Post
Without using positive and negative controls it is simply impossible to fulfill the scientific requirements (means to show that it is valid).

Without that the result of any test is only "null hypothesis could not be rejected" or "null hypothesis could be rejected" but no further conclusions about the reasons for these results can be drawn, which means that the test is quite useless.
First sentence: Yes, where appropriate. It depends on the question being asked and the variable examined. Otherwise, this is just a mantra.

Second sentence: The first part is correct (and appropriate to the question, "Can listener X hear the difference between two preamps in a setup where he claims the differences are readily audible?"). Either he can (null hypothesis rejected) or he can't (null hypothesis not rejected). The second part is a nonsequitur- it's very useful for answering questions of this type.

Being specific about the question asked by an experiment is a necessary first step to prevent confusion of the sort you're having.
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Old 10th September 2012, 10:40 AM   #27484
Jakob2 is offline Jakob2  Germany
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First sentence: Yes, where appropriate. It depends on the question being asked and the variable examined. Otherwise, this is just a mantra.
We are talking about audible differences between two DUTs and we are talking about the test protocols normally used.
One other possible method, where the participants did not know about being tested, i have described before.

Btw, scientific rules are indeed sort of a mantra and for an ABX there exists no other way to show the validity wrt to our discussions.

Of course if an experimenter is researching the hypothesis that a difference is audible under just any condition by every listener, than a positive control is not needed (but a negative control is still mandatory).

Quote:
Second sentence: The first part is correct (and appropriate to the question, "Can listener X hear the difference between two preamps in a setup where he claims the differences are readily audible?"). Either he can (null hypothesis rejected) or he can't (null hypothesis not rejected). The second part is a nonsequitur- it's very useful for answering questions of this type.
Iīm sorry but our concern isnīt normally if a specific listener can detect something, but if an audible difference between two DUTs exists and that is a very different question.

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Being specific about the question asked by an experiment is a necessary first step to prevent confusion of the sort you're having.
That was the reason why iīve wrote a lot of posts about operationalisation in test design to bring (back) that concept to (your) attention and we know that in the past (in most cases) a definite question wasnīt established before testing for amplifier and other differences.
It does not help (well of course that depends on the experimenters bias) to adjust the question afterwards to meet the results.
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Old 10th September 2012, 11:21 AM   #27485
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Well, you're asking a different question than I am. And actually, several different questions mashed together, each of which need to be answered in different ways. No wonder there's such a big cloud of dust!
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Old 10th September 2012, 12:13 PM   #27486
zinsula is offline zinsula  Switzerland
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Quote:
Originally Posted by Jakob2 View Post
[...]Iīm sorry but our concern isnīt normally if a specific listener can detect something, but if an audible difference between two DUTs exists and that is a very different question.[...]
Seems perfectly reasonable to me. One clear question.

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Well, you're asking a different question than I am. And actually, several different questions mashed together, each of which need to be answered in different ways. No wonder there's such a big cloud of dust!
Now I'm confused.
Jakob has pointed out one question.
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Old 10th September 2012, 12:16 PM   #27487
Jakob2 is offline Jakob2  Germany
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Well, you're asking a different question than I am. And actually, several different questions mashed together, each of which need to be answered in different ways. No wonder there's such a big cloud of dust!
Could you be more specific regarding the different questions that are mashed together?

I donīt know if it were different questions in every case, but if youīre asking if a listener can detect a difference in a test (under the premise that he claims to hear a difference under different conditions), then you still would have to show that the independent variable in your test will be only an audible difference but not the disability to detect the difference under test conditions.


Quote:
<snip>(and appropriate to the question, "Can listener X hear the difference between two preamps in a setup where he claims the differences are readily audible?"). Either he can (null hypothesis rejected) or he can't (null hypothesis not rejected).
It ist only appropriate if you have shown first the validity of the test, otherwise the corrected question would be "can listener X hear the difference between two preamps _under_ _test_ _conditions_ in a setup where he claims the difference are readily audibel?")



Quote:
The second part is a nonsequitur- it's very useful for answering questions of this type.
It is an answer to these questions, _if_ the test is objective, valid and reliable.
Otherwise you canīt draw any conclusions and the result would just be the "null hypothesis could...." result as descripted.

Last edited by Jakob2; 10th September 2012 at 12:20 PM.
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Old 10th September 2012, 12:53 PM   #27488
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Originally Posted by Jakob2 View Post

I donīt know if it were different questions in every case, but if youīre asking if a listener can detect a difference in a test (under the premise that he claims to hear a difference under different conditions), then you still would have to show that the independent variable in your test will be only an audible difference but not the disability to detect the difference under test conditions.
This isn't my question, this should be the question asked by someone who claims sonic superiority of their product or technology. My question was the one you dismissed.

Quote:
Iīm sorry but our concern isnīt normally if a specific listener can detect something...
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Old 10th September 2012, 01:11 PM   #27489
Jakob2 is offline Jakob2  Germany
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This isn't my question, this should be the question asked by someone who claims sonic superiority of their product or technology. My question was the one you dismissed.
Ahh, not dismissing something, just sorting out, due to a given uncertainty.

So, did "the" listener claim to hear a difference under the specific blind test conditions?
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Old 10th September 2012, 01:40 PM   #27490
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The listener claims he can hear differences under sighted conditions, unrelated to frequency response and level, with his choice of material and with his system. Like every other listener who has made such a claim, he has yet to demonstrate he can do it by ear alone. Like most others who feel their reputation is at stake, he does not want to test his hypothesis.

Really, there's no need to obfuscate a very simple question.
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