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What's the problem with double-blind testing?
mirrorsawlljk
post Oct 19 2005, 03:03
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I happened to pick up an issue of stereophile at a record store I visited and I was pretty shocked to see a seemingly intelligent person in the correspondence section bashing double blind testing as being unreliable. I'm afraid I don't understand his angle of attack. I don't see how anything could be a more reliable test of sound quality differences than a properly conducted double blind listening test.

I'm almost afraid to read the rest of the magazine if this is the kind of letter they think is worth publishing. Is there an audio magazine that isn't filled with this kind of thinking?
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ff123
post Oct 19 2005, 20:53
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Tests that try to distinguish very small effects *and* aim for small type I and type II errors either require lots of listeners or lots of trials. See my test sensitivity calculator:

http://ff123.net/export/TestSensitivityAnalyzer.xls

Column "D" shows the Proportion of Distinguishers, that is, the proportion of listeners in a randomly sampled group of people who would be expected to hear a difference in an audio comparison. The smaller the proportion of distinguishers, the smaller the effect. If the proportion of distinguishers is 30% (a pretty small effect), you'd need 119 listeners out of which 69 have to make a correct response to limit both the type I and type II errors to 0.05. I assume this would be the criteria that would satisfy both the "objective" and the "subjective" crowds.

But obviously there is already a huge problem in trying to assemble that many listeners or in attempting such a large number of trials.

ff123
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Posts in this topic
- mirrorsawlljk   What's the problem with double-blind testing?   Oct 19 2005, 03:03
- - bubka   some people can actually detect specific codecs by...   Oct 19 2005, 03:07
- - TheQat   QUOTE (mirrorsawlljk @ Oct 18 2005, 06:03 PM)...   Oct 19 2005, 03:27
|- - singaiya   QUOTE (TheQat @ Oct 18 2005, 06:27 PM)QUOTE (...   Oct 19 2005, 04:31
|- - Yaztromo   QUOTE (TheQat @ Oct 19 2005, 03:27 AM)Edit: H...   Oct 19 2005, 23:05
- - Tahnru   The closest thing I have seen to a legitimate crit...   Oct 19 2005, 04:29
- - Axon   The Audio Critic is notably pro-DBT.   Oct 19 2005, 07:06
|- - PoisonDan   QUOTE (Axon @ Oct 19 2005, 08:06 AM)The Audio...   Oct 19 2005, 12:18
- - onthejazz   Interesting publication. I like it, too bad its no...   Oct 19 2005, 10:03
|- - Donunus   The writer of the letter in stereophile is incorre...   Oct 19 2005, 11:00
|- - Danimal   QUOTE (Donunus @ Oct 19 2005, 05:00 AM)The wr...   Oct 19 2005, 20:20
|- - Donunus   QUOTE (Danimal @ Oct 20 2005, 03:20 AM)QUOTE ...   Oct 20 2005, 01:51
|- - stephanV   QUOTE (Donunus @ Oct 20 2005, 02:51 AM)Well, ...   Oct 20 2005, 08:48
||- - bryant   QUOTE (stephanV @ Oct 19 2005, 11:48 PM)QUOTE...   Oct 20 2005, 18:11
|||- - Pio2001   QUOTE (bryant @ Oct 20 2005, 07:11 PM)To tell...   Oct 20 2005, 20:48
||||- - singaiya   Thanks for the papers, David. The first one is a g...   Oct 20 2005, 22:13
||||- - duff   QUOTE (Pio2001 @ Oct 20 2005, 07:48 PM)QUOTE ...   Oct 20 2005, 22:52
||||- - stephanV   QUOTE (duff @ Oct 20 2005, 11:52 PM)It's ...   Oct 20 2005, 23:11
|||||- - duff   QUOTE Might be... or might be not. You can't c...   Oct 20 2005, 23:36
|||||- - KikeG   QUOTE (duff @ Oct 20 2005, 11:36 PM)I think i...   Oct 21 2005, 00:00
||||||- - rjamorim   QUOTE (KikeG @ Oct 20 2005, 09:00 PM)Also, ps...   Oct 21 2005, 00:15
||||||- - duff   QUOTE (KikeG @ Oct 20 2005, 11:00 PM)QUOTE (d...   Oct 21 2005, 00:29
||||||- - rjamorim   QUOTE (duff @ Oct 20 2005, 09:29 PM)I'm n...   Oct 21 2005, 01:03
||||||- - Mike Giacomelli   QUOTE (duff @ Oct 20 2005, 04:29 PM)The audit...   Oct 21 2005, 05:56
||||||- - KikeG   QUOTE (duff @ Oct 21 2005, 12:29 AM)From the ...   Oct 21 2005, 08:10
|||||- - stephanV   QUOTE (duff @ Oct 21 2005, 12:36 AM)I think i...   Oct 21 2005, 08:34
|||||- - Woodinville   QUOTE (stephanV @ Oct 20 2005, 11:34 PM)Sorry...   Oct 21 2005, 21:19
||||- - krabapple   QUOTE (duff @ Oct 20 2005, 04:52 PM)QUOTE (Pi...   Oct 21 2005, 05:25
||||- - antz   QUOTE (duff @ Oct 20 2005, 10:52 PM)QUOTE (Pi...   Oct 21 2005, 13:39
||||- - Woodinville   QUOTE (antz @ Oct 21 2005, 04:39 AM)Seems to ...   Oct 21 2005, 21:20
|||- - stephanV   QUOTE (bryant @ Oct 20 2005, 07:11 PM)It turn...   Oct 20 2005, 21:43
||- - Donunus   QUOTE (stephanV @ Oct 20 2005, 03:48 PM)QUOTE...   Oct 21 2005, 04:10
||- - stephanV   QUOTE (Donunus @ Oct 21 2005, 05:10 AM)I do n...   Oct 21 2005, 08:43
||- - user   I recall, we have had successful abx tests even he...   Oct 21 2005, 09:20
||- - Pio2001   QUOTE (user @ Oct 21 2005, 10:20 AM)I recall,...   Oct 21 2005, 12:18
|||- - ff123   QUOTE (Pio2001 @ Oct 21 2005, 03:18 AM)QUOTE ...   Oct 21 2005, 17:43
||- - krabapple   QUOTE (user @ Oct 21 2005, 03:20 AM)I recall,...   Oct 21 2005, 21:54
|- - Cartoon   QUOTE (Donunus @ Oct 20 2005, 02:51 AM)I do h...   Nov 12 2005, 13:40
- - KikeG   The "goosebump", emotional factor can be...   Oct 19 2005, 11:54
|- - Donunus   QUOTE (KikeG @ Oct 19 2005, 06:54 PM)The ...   Oct 19 2005, 12:06
|- - kjoonlee   QUOTE (Donunus @ Oct 19 2005, 08:06 PM)actual...   Oct 19 2005, 18:31
||- - Woodinville   QUOTE (kjoonlee @ Oct 19 2005, 09:31 AM)QUOTE...   Oct 21 2005, 01:27
||- - duff   QUOTE If you consider that we are wired to detect ...   Oct 21 2005, 01:38
||- - Woodinville   QUOTE (duff @ Oct 20 2005, 04:38 PM)So we are...   Oct 21 2005, 21:15
||- - duff   QUOTE (Woodinville @ Oct 21 2005, 08:15 PM)QU...   Oct 21 2005, 23:43
||- - Woodinville   QUOTE (duff @ Oct 21 2005, 02:43 PM)When I sa...   Oct 22 2005, 08:00
|- - Lyx   QUOTE (Donunus @ Oct 19 2005, 01:06 PM)QUOTE ...   Oct 20 2005, 06:07
|- - Donunus   QUOTE (Lyx @ Oct 20 2005, 01:07 PM)QUOTE (Don...   Oct 20 2005, 16:51
|- - Lyx   QUOTE (Donunus @ Oct 20 2005, 05:51 PM)QUOTE ...   Oct 20 2005, 21:10
- - KikeG   Well, I think expectation effects in listening tes...   Oct 19 2005, 19:33
|- - krabapple   QUOTE (KikeG @ Oct 19 2005, 10:33 AM)Well, I ...   Oct 19 2005, 20:12
- - krabapple   QUOTE (mirrorsawlljk @ Oct 18 2005, 06:03 PM)...   Oct 19 2005, 20:06
- - Halcyon   There is nothing inherently bad about double blind...   Oct 19 2005, 20:29
- - ff123   Tests that try to distinguish very small effects *...   Oct 19 2005, 20:53
|- - krabapple   QUOTE (ff123 @ Oct 19 2005, 11:53 AM)Tests th...   Oct 19 2005, 23:40
|- - ff123   QUOTE (krabapple @ Oct 19 2005, 02:40 PM)Inte...   Oct 20 2005, 05:38
- - fcmts   There is another problem similar to wine blind tes...   Oct 19 2005, 22:15
- - stephanV   I don't see how that is a problem. The goal of...   Oct 19 2005, 22:22
- - duff   One distinction relevant to this issue is the diff...   Oct 20 2005, 23:00
- - duff   QUOTE The opposite of "blind", I suppose...   Oct 21 2005, 01:27
- - Jun-Dai   I think it's pretty clear that double-blind te...   Oct 21 2005, 07:22
- - KikeG   For helping doing long-term, casual listening-like...   Oct 21 2005, 08:30
- - duff   QUOTE Seems to be a lack of understanding of somet...   Oct 21 2005, 16:48
|- - stephanV   QUOTE (duff @ Oct 21 2005, 05:48 PM)The reaso...   Oct 21 2005, 17:29
||- - duff   QUOTE (stephanV @ Oct 21 2005, 04:29 PM)QUOTE...   Oct 21 2005, 20:06
||- - stephanV   QUOTE (duff @ Oct 21 2005, 09:06 PM)QUOTE Wh...   Oct 21 2005, 20:21
||- - bryant   QUOTE (stephanV @ Oct 21 2005, 11:21 AM)QUOTE...   Oct 21 2005, 22:53
||- - rjamorim   QUOTE (bryant @ Oct 21 2005, 07:53 PM)But I d...   Oct 21 2005, 23:12
||- - stephanV   QUOTE (bryant @ Oct 21 2005, 11:53 PM)So, if ...   Oct 22 2005, 00:00
||- - ChiGung   QUOTE (bryant @ Oct 21 2005, 10:53 PM)What...   Oct 22 2005, 00:25
|||- - bryant   QUOTE (ChiGung @ Oct 21 2005, 03:25 PM)I have...   Oct 22 2005, 23:39
|||- - ChiGung   just thinking -i do get all sorts of weird sensati...   Oct 23 2005, 00:34
||- - Woodinville   QUOTE (bryant @ Oct 21 2005, 01:53 PM)So, if ...   Oct 22 2005, 07:52
||- - bryant   QUOTE (Woodinville @ Oct 21 2005, 10:52 PM)QU...   Oct 22 2005, 23:32
||- - Woodinville   QUOTE (bryant @ Oct 22 2005, 02:32 PM)The onl...   Oct 24 2005, 21:51
|- - Lyx   QUOTE (duff @ Oct 21 2005, 05:48 PM)QUOTE See...   Oct 21 2005, 17:35
|- - krabapple   QUOTE (duff @ Oct 21 2005, 10:48 AM)QUOTE See...   Oct 21 2005, 22:01
- - duff   QUOTE It sounds counterintuitive that my brain wou...   Oct 22 2005, 00:30
|- - ChiGung   QUOTE (duff @ Oct 22 2005, 12:30 AM)Frankly, ...   Oct 22 2005, 00:47
||- - duff   QUOTE (ChiGung @ Oct 21 2005, 11:47 PM)QUOTE ...   Oct 22 2005, 01:14
||- - ChiGung   QUOTE (duff @ Oct 22 2005, 01:14 AM)The reduc...   Oct 22 2005, 01:26
|- - Woodinville   QUOTE (duff @ Oct 21 2005, 03:30 PM)Filtering...   Oct 22 2005, 08:07
- - ChiGung   A simplistic example - a sine wave of exactly 3122...   Oct 22 2005, 00:59
|- - Woodinville   QUOTE (ChiGung @ Oct 21 2005, 03:59 PM)A simp...   Oct 22 2005, 08:08
|- - ChiGung   QUOTE (Woodinville @ Oct 22 2005, 08:08 AM)QU...   Oct 22 2005, 14:09
- - ChiGung   -Sorry for flooding a bit there. Tasty subject   Oct 22 2005, 01:01
- - duff   So sorry for the long delay. I didn't forget a...   Nov 10 2005, 20:10
|- - Woodinville   QUOTE (duff @ Nov 10 2005, 11:10 AM)Woodinsid...   Nov 10 2005, 20:23
- - duff   I don't understand why you would want to maint...   Nov 11 2005, 00:41
|- - Woodinville   QUOTE (duff @ Nov 10 2005, 03:41 PM)Somehow, ...   Nov 11 2005, 21:52
|- - Pio2001   QUOTE (duff @ Nov 11 2005, 01:41 AM)The ABX p...   Nov 12 2005, 03:00
|- - Woodinville   QUOTE (Pio2001 @ Nov 11 2005, 06:00 PM)I can ...   Nov 12 2005, 09:33
|- - user   There aren't theoretical flaws with abx or DB ...   Nov 12 2005, 10:52
- - KikeG   Sorry, you still have provided no evidence that wh...   Nov 11 2005, 14:34
|- - Woodinville   QUOTE (KikeG @ Nov 11 2005, 05:34 AM)Sorry, y...   Nov 11 2005, 21:56
|- - Pio2001   QUOTE (Woodinville @ Nov 11 2005, 10:56 PM)Su...   Nov 12 2005, 02:32
- - duff   Let's back up a moment... There are at least ...   Nov 11 2005, 18:37
- - KikeG   About the first point, your degraded examples are ...   Nov 11 2005, 19:57
- - duff   QUOTE Well, if it's inaudible, there's a g...   Nov 11 2005, 21:19
- - Woodinville   QUOTE (duff @ Nov 11 2005, 12:19 PM)In other ...   Nov 11 2005, 21:59
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