
Home  Forums  Rules  Articles  diyAudio Store  Blogs  Gallery  Wiki  Register  Donations  FAQ  Calendar  Search  Today's Posts  Mark Forums Read  Search 
The Lounge A place to talk about almost anything but politics and religion. 

Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving 

Thread Tools  Search this Thread 
Today, 08:41 AM  #9981  
diyAudio Member
Join Date: Aug 2014

Quote:
Quote:


Today, 08:50 AM  #9982  
diyAudio Member
Join Date: Apr 2002
Location: Prague

Quote:
I would understand if you complained against validity of a positive result, but why against negative result? Just a suspicion?
__________________
Pavel Macura http://pmacura.cz/audiopage.html https://www.diyaudio.com/forums/ever...cordtest.html 

Today, 09:01 AM  #9983  
diyAudio Member
Join Date: Apr 2002
Location: Prague

Quote:
I guess that any kind of measurements or file analysis is not enough for you.
__________________
Pavel Macura http://pmacura.cz/audiopage.html https://www.diyaudio.com/forums/ever...cordtest.html 

Today, 09:05 AM  #9984 
diyAudio Member
Join Date: Aug 2014

@PMA, what I'm pointing out is that your statement "absolutely free choice of almost anything," really doesn't stand up to scrutiny & the very fact that participants know they are being 'tested' is an overriding stressor. So I don't about you are free argument, either.
As I & & others have said, a relaxed listening to many types of music over some extended period is far different to what you are doing. I also just have to point out the underlying bias that is seen in this form of testing  you just spent to some lengths in your latest test files to eliminate 'cheating' by too high a volume, yet you dismiss any effort to test the sensitivity of the test itself. This bias is also seen in the writers of Foobar ABX who updated it a while back adding on anticheating measures (log file checksum) but not paying the slightest effort in implementing hidden controls  it would be easy for the ABX utility implement the hidden control I suggested. All the efforts are to minimise positive results  no effort to validate the test itself Last edited by mmerrill99; Today at 09:10 AM. 
Today, 09:15 AM  #9985  
diyAudio Member
Join Date: Aug 2014

Quote:
Quote:


Today, 09:21 AM  #9986  
diyAudio Member
Join Date: Jun 2004
Location: germany

Quote:
Unfortunately you must have a log of the trials to know what was presented as "A, B and X" and to look for some patterns in the results. Quote:
Good questions what the reason for having nonpositive ABX results is; usually an experiment should be designed to help answer those questions, but as you might remember, if it canīt be shown that a test is objective, reliable and valid you canīt draw further conclusions from the results. Thatīs the reason why the test is done and still the questions remain. Last edited by Jakob2; Today at 09:24 AM. 

Today, 09:43 AM  #9987  
diyAudio Moderator

Quote:
Quote:
Quote:
__________________
["Second Law is a bitch."  SY] ["I insist on respecting the means of the average person working in their garage/basement." Scott Wurcer] 

Today, 09:47 AM  #9988 
diyAudio Member
Join Date: Jun 2004
Location: germany

@ PMA,
we addressed the question for a positive control in the other threads already quite extensive. The level difference is a good one, as listeners usually (means in a multidimensional evaluation) , if the level difference gets small between the samples, donīt recognize it as a level difference but as a sound difference. It depends on the experience, at first listeners may have difficulties to recognize a level difference of 1 dB as such, while experienced listeners will still be able to do it. Below 0.3 dB it gets more and more difficult and thatīs usually the region where imE all listeners only notice the sound difference but not the level difference as such. So using level difference at different niveaus even allows to monitor the effect of training. Wrt the sample size needed; what Leventhal did was to reinvent the power analysis concept that Jacob Cohen revided already in the mid 1960s. To reach the usual SL = 0.05 you donīt 16 samples (thatīs why our preamplifier could be used although there were only two tests of 5 samples done) and wrt statistical power 16 samples do not really help either. Iīve posted some power calculations before, so only in short now; if you want a power of at leas 0.8 and want still be able to get positive results for low detecting abilities under the test conditions, then it the variables are: power = 0.8 SL = 0.05 p2 = 0.6 p = 0.5 and therefore the sample size needed would be 158. Otoh, we could calculate the power that results for the same variables but a given sample size of 16: SL= 0.05 p2 = 0.6 p = 0.5 sample size = 16 and then the actual power will be 0.167. Which means the chance to miss this difference (which _is_ perceptable, so the null hypothesis must be rejected) is a whopping 83.3 % . If you would like to balance SL and statistical power to have the same error risk in all cases, things are getting even more worse. Small effects, as DPH already mentioned, to detect is difficult. 
Today, 09:57 AM  #9989 
diyAudio Member
Join Date: Aug 2014

Thanks, Jakob2 & you are correct but let's keep it simple  I would be interested in the results of hidden controls from the typical ABX tests run here.

Thread Tools  Search this Thread 


New To Site?  Need Help? 