Stewart Pinkerton wrote:

On 18 Dec 2004 23:32:41 GMT, wrote:

But what I fail to understand is how the statistics _know_ what
the device under test is? How, when testing loudspeakers for
example, a 95% probability of the results not being due to random
guessing can be taken as probably meaning there is a real sonic
difference, but in the case of amplifiers it cannot.

Yes, in your _opinion_, Mr. Nousaine, there is no reason for
amplifiers to sound different, but as has been pointed out before,
your opinion carries no special weight over anyone else's.

I can't speak for Tom, but there has been in existence for about six
years, a $5,000 prize awaiting anyone who can differentiate two cables
in a level-matched DBT, in any system of their choice and with any
music of their choice. The bar has been set at 15 or more correct out
of 20 trials, and that has not changed. Interestingly, despite many
claims of 'night and day' differences, there have been no contenders.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

High-enders tend to be cafe racers. They have all night and day to proclaim
this and that but try to get them out on the track and they'll argue that a
stop watch desensitizes them and causes so much pressure that it interferes
with their physical senses. IMO it is true that there is a good deal of
pressure on those who make unsubstantiated claims when they might be asked to
prove it.

It's much easier to argue over old experiments and how they were "really"
positive even when the statistics say otherwise.

On 12/19/04 12:55 PM, in article , "Ed
Seedhouse" wrote:

In fact I'd say myself that it's the purveyors of so-called
"subjectivism" here, if anyone, who claim to be the "purveyors of
absolute truth". They have beliefs about sound quality that, it
appears to me, they won't change no matter how much evidence
accumulates against them.

Part of being a subjectivist is that you can present one with 20 reams of
data showing that some piece of gear is sub-par, but if they like how it
actually sounds and they think it helps them recreate the live performances
they crave to hear it is only so much recycling.

I totally agree that it is impossible to design audio components without
good objective targets and guidelines as well as good engineering that,
again involved measurement and theory. When someone goes to buy the
component, however, it is unlikely they will take anything more than their
ears and perhaps a tape measure to see if it will fit in their living room
space.

The ear is a very important instrument - the most important one, actually,
but the brain is a rather subjective filter to begin with, too and therein
lies the conundrum.

On 12/19/04 1:50 PM, in article , "Stewart
Pinkerton" wrote:

On 19 Dec 2004 15:56:47 GMT, B&D wrote:

On 12/18/04 6:32 PM, in article ,
"
wrote:

ABX box where I identified absolute polarity 18
times out of 20, which exceeds the 99% confidence level.

Isn't 18/20 90%? Still not a bad result, and one that I would start paying
attention to absolute polarity, BTW, but what is 99% confidence?

No, you need to look up basic statistics. 18 correct out of twenty
'coin tosses' is *way* better than 90% probability of a detectable
difference.

Ah, misread it - if I select coprrectly 18 times out of 20 times - then I am
a 90% accurate detector.

"one of the reasons you rejected the results of a blind test I took
in 1984 using an ABX box where I identified absolute polarity 18
times out of 20, which exceeds the 99% confidence level. (You have"

In which case you suggest confidence in both the testing method and
confidence to have abilities to hear differences during same. Can we then
know why you refuse to do such testing on wire, stands, etc. to establish
that the subjective enterprise has a reality other then those perceptions
originating in the brain alone? You have said you have no reason to be
tested but seem to do so because you are satisfied of your nudemonstrated
ability to do so and/or for any motivation to do so for publishing
reasons. Have you no scientific curiosity, even if you never make the
results appear in print? Or is that the reality, you have done such
testing and/or done such to others and wish the results not to be known?

"Yes, in your _opinion_, Mr. Nousaine, there is no reason for
amplifiers to sound different, but as has been pointed out before,
your opinion carries no special weight over anyone else's.
John Atkinson"

Opinion is not relevant when he only referes to an established benchmark
of hearing alone testing which shows no reason to reject the conclusion
that amps don't sound different, within the parameters often expressed.
Views of using the benchmark is opinion, the collective results are not.
This is what defines science in part, we don't have to rely on opinion of
authorties just because they are seen as such, the research speaks for
itsef even if the author of it were not known. Conclusions based on
opinion, such as you suggest, are as common and in number to the content
of any local bar on any night. Demonstrated evidence used well in support
of valid conclusions flowing from it are quite another thing. You have
and I have an opinion is ok at the bar, in pursuit of validity in the
realy world no such egalatarian ground serves.

Hi Ed,

That was the impression I got from those here who
have
such high esteem for him.

I've read all those posts and didn't get any such
impression. I don't
think that any reasonably rational person who read
them without
predjudice could get any such impression.

Then I got the wrong impression (I have not read ALL
the posts). My impression of Randi has been that he is
a "debunker of fraud", essentially a "truth-seeker" who
aspires to publish the absolute truth. I didn't
realize this could be interpeted as name-calling.

If that's what you consider to be name-calling,
then I admit it

I think any reasonably disinterested party familiar
with the common
falacies of argument would call it that.

I guess you're right. I am interested (thus the post),
and I am not "familiar with the common falacies of
argument". (You must have been an English major. I'm
just a firmware engineer - the only arguments I know
about are the ones I pass to subroutines ;^)

though it appears that you have insulted him more
than I ;^)

Huh?

I wrote, "...Randi, the publisher of the absolute
truth...", and you replied, "In fact I've read his
stuff for years and it's
rather the opposite." My impression was that Randi
would not object to my characterization of him, but he
would not care for yours. Obvioulsy we tend to have
opposite impressions.

I encourage Randi in his endeavors; I just think he
(and
others) could have handled this better.

In retrospect, on just about any issue at all, it
will virtually
unanimously be seen that all sides could have handled
things better.
Thus, your comment above appears to me to be devoid
of content.

I bet'cha that's some more of that "common falacies of
argument" stuff again. Stop showing off.

Sorry if I got your dander up.

My "dander" has nothing to do with it. Your name
calling did.

I'm sure you have chastised those posters who called
John Atkinson a "snake oil salesman" just as harshly as
you did me for calling Randi "publisher of the absolute
truth" (I'm sorry I missed your posts).

Regards,
Tip

"Steven Sullivan" wrote in message
...

From my own experiences with inadvertant 'phantom switching' -- where
I thought something had changed, with a concomitant 'obvious' change
in sound, only to find that nothign had really changed -- I know that
having experienced it once doens't mean I never experience it again!

Are you certain that the (exact) position of your ears didn't change?

On 20 Dec 2004 00:38:46 GMT, "Tip" wrote:

Then I got the wrong impression (I have not read ALL
the posts). My impression of Randi has been that he is
a "debunker of fraud", essentially a "truth-seeker"

Well, that's one aspect of what he does and writes about.

who aspires to publish the absolute truth.

His position is actually generally in accord with the so-called
"scientific method". One important fact about science is that it
generally doesn't claim to produce any absolute truths. and I have
*never* read any claim by Randi that he is in any way infallible.

I am interested (thus the post),
and I am not "familiar with the common falacies of
argument".

Then you are uneducated, no matter what degrees you might hold.

(You must have been an English major.

I'm a high school graduate of the early 1960's and didn't major in
English. I can also read. A good education is available to anyone
who has a Public Library in their vicinity. I took advantage of that
to, among other things, read up on what does and what does not
constitute a good rational argument.

I wrote, "...Randi, the publisher of the absolute
truth...", and you replied, "In fact I've read his
stuff for years and it's rather the opposite." My
impression was that Randi would not object to
my characterization of him,

Actually I am confident that he would be deeply and justifiably
insulted by it - as would I if you applied it to me, since it is
clearly intended to be ironically insulting.

but he
would not care for yours. Obvioulsy we tend to have
opposite impressions.

But *you* admit you have read hardly anything he has written. I, on
the other hand have read many articles by him and several of his
books. I have, in other words, accumulated some evidence.

I'm sure you have chastised those posters who called
John Atkinson a "snake oil salesman" just as harshly as
you did me for calling Randi "publisher of the absolute
truth" (I'm sorry I missed your posts).

I didn't criticise you harshly at all, actually. I merely said that
you were name calling, which I still believe you were in fact doing.

On the other hand it is certainly true that JA makes a living for,
among other things, accepting and publishing advertisements for
products that I personally think can justifiably be called "snake
oil". As does one of our local radio stations around where I live,
which accepts advertisements for "magnetic" matresses.

Ed

B&D wrote:
On 12/19/04 1:50 PM, in article , "Stewart
Pinkerton" wrote:

On 19 Dec 2004 15:56:47 GMT, B&D wrote:

On 12/18/04 6:32 PM, in article ,
"
wrote:

ABX box where I identified absolute polarity 18
times out of 20, which exceeds the 99% confidence level.

Isn't 18/20 90%? Still not a bad result, and one that I would start paying
attention to absolute polarity, BTW, but what is 99% confidence?

No, you need to look up basic statistics. 18 correct out of twenty
'coin tosses' is *way* better than 90% probability of a detectable
difference.

Ah, misread it - if I select coprrectly 18 times out of 20 times - then I am
a 90% accurate detector.

I don't think it is a case of misreading. And I don't think you
understand the principles of statistics yet. If you select correctly 18
times out of 20 times, then there is a very high probability (much more
than 90%) that you are not guessing and that there is some real
detectable difference.

Have they stopped teaching statistics in undergraduate engineering
curriculum these days?

On 12/19/04 7:38 PM, in article , "Tip"
wrote:

I've read all those posts and didn't get any such
impression. I don't
think that any reasonably rational person who read
them without
predjudice could get any such impression.

Then I got the wrong impression (I have not read ALL
the posts). My impression of Randi has been that he is
a "debunker of fraud", essentially a "truth-seeker" who
aspires to publish the absolute truth. I didn't
realize this could be interpeted as name-calling.

I have always had a question of Randi's "mission" - he is a debunker, but I
am not convinced that he really does aspire to publish absolute truth - he
has shown a great reluctance to set the record straight according the
Atkinson of Stereophile, when is was shown that he made a number of errors
of fact because his fans were "wearied" but had no issue with right after
that continuing a diatribe along those very lines. Makes me think that he
is more about entertainment than truth which is a shame.

B&D wrote:

On 12/19/04 12:55 PM, in article , "Ed
Seedhouse" wrote:

In fact I'd say myself that it's the purveyors of so-called
"subjectivism" here, if anyone, who claim to be the "purveyors of
absolute truth". They have beliefs about sound quality that, it
appears to me, they won't change no matter how much evidence
accumulates against them.

Part of being a subjectivist is that you can present one with 20 reams of
data showing that some piece of gear is sub-par, but if they like how it
actually sounds and they think it helps them recreate the live performances
they crave to hear it is only so much recycling.

I totally agree that it is impossible to design audio components without
good objective targets and guidelines as well as good engineering that,
again involved measurement and theory. When someone goes to buy the
component, however, it is unlikely they will take anything more than their
ears and perhaps a tape measure to see if it will fit in their living room
space.

That's why we say that you could choose your equipment whichever way you
like.


The ear is a very important instrument - the most important one, actually,
but the brain is a rather subjective filter to begin with, too and therein
lies the conundrum.

There is no conundrum. When it comes to whether the sound is different
or not, simply listen with ears only. Note that the believers are saying
that the sound is different, but then they fail to back that up with
measurements or bias-controlled testing.

On 20 Dec 2004 03:55:03 GMT, B&D wrote:

I have always had a question of Randi's "mission" - he is a debunker, but I
am not convinced that he really does aspire to publish absolute truth

Well that's hardly surprising. Who knows the "absolute" truth? Not
I, and not Randi.

Is there in fact any such thing as "absolute" truth? I don't think
there is, and I believe most scientists don't either. As far as I
know science in general makes absolutely *no* claim to discover
"absolute" truth.

In fact, if Randi were to claim that he is seeking absolute truth that
alone would make him very suspect indeed, in my eyes at least.

Ed

On 20 Dec 2004 00:30:57 GMT, B&D wrote:

On 12/19/04 1:50 PM, in article , "Stewart
Pinkerton" wrote:

On 19 Dec 2004 15:56:47 GMT, B&D wrote:

On 12/18/04 6:32 PM, in article ,
"
wrote:

ABX box where I identified absolute polarity 18
times out of 20, which exceeds the 99% confidence level.

Isn't 18/20 90%? Still not a bad result, and one that I would start paying
attention to absolute polarity, BTW, but what is 99% confidence?

No, you need to look up basic statistics. 18 correct out of twenty
'coin tosses' is *way* better than 90% probability of a detectable
difference.

Ah, misread it - if I select coprrectly 18 times out of 20 times - then I am
a 90% accurate detector.

No. If you get 18 correct out of 20, there is a better than 99% chance
that there was something detectable. 90% would be at about 14 correct
out of 20, but it would need only about 60 out of 100 (or thereabouts
- sorry, can't do stats in my head any more, but you get the idea -
probability increases with the number of trials)

You can't do probability calculations by simple division. BTW, note
that a 95% probability is exactly that - a probability. If you toss a
coin twenty times and get 15 heads, then that will happen on average
once every twenty times you try it. So, getting that score in a cable
comparison isn't absolute proof, it's just a generally accepted
benchmark. Makes me wonder why nobody's tried to win the prize just by
sheer guessing! :-)

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Ed Seedhouse wrote:
On 20 Dec 2004 00:38:46 GMT, "Tip" wrote:
I'm sure you have chastised those posters who called
John Atkinson a "snake oil salesman" just as harshly as
you did me for calling Randi "publisher of the absolute
truth" (I'm sorry I missed your posts).

...it is certainly true that JA makes a living for, among
other things, accepting and publishing advertisements for
products that I personally think can justifiably be called
"snake oil".

Please note, Mr. Seedhouse, that I have no control over any
what ads appear in Stereophile. The "Chinese Wall" that
separates a magazine's advertising department from its
editorial staff also operates in the opposite direction. I
have no knowledge about the ads that appear in an issue of
Stereophile until I receive my printed copy.
John Atkinson
Editor, Stereophile

"Stewart Pinkerton" wrote in message
...
On 18 Dec 2004 23:32:41 GMT,
wrote:

But what I fail to understand is how the statistics _know_ what
the device under test is? How, when testing loudspeakers for
example, a 95% probability of the results not being due to random
guessing can be taken as probably meaning there is a real sonic
difference, but in the case of amplifiers it cannot.

Yes, in your _opinion_, Mr. Nousaine, there is no reason for
amplifiers to sound different, but as has been pointed out before,
your opinion carries no special weight over anyone else's.

I can't speak for Tom, but there has been in existence for about six
years, a $5,000 prize awaiting anyone who can differentiate two
cables
in a level-matched DBT, in any system of their choice and with any
music of their choice. The bar has been set at 15 or more correct
out
of 20 trials, and that has not changed. Interestingly, despite many
claims of 'night and day' differences, there have been no
contenders.

After playing around with my calculator, I notice that you have a
50-50 chance of losing your $5000 after 32 people have taken the test.
You should collect $20 for the privilege of taking the test. Even
unlikely things happen every so often.

Norm Strong

Hi Ed,

...I am not "familiar with the common falacies of
argument".

Then you are uneducated, no matter what degrees you
might hold.

I thought you had dug yourself into a hole and I was
allowing you to get out of it. You don't think anyone
actually bought that "common falacies of argument"
rhetoric, did you?

I wrote, "...Randi, the publisher of the absolute
truth...", and you replied, "In fact I've read his
stuff for years and it's rather the opposite." My
impression was that Randi would not object to
my characterization of him,

Actually I am confident that he would be deeply and
justifiably
insulted by it - as would I if you applied it to me,
since it is
clearly intended to be ironically insulting.

Thank you - that solves the mystery. "Truth" is in the
eye of the beholder. As you mentioned, the
"subjectivists" believe they are telling the "truth".
I should have said "facts" instead of "absolute truth"
to make my intentions clear. My dictionary defines "an
absolute truth" as "not doubted; actual; real" - there
was no mention of "irony". However, I appreciate your
explanation of how the scientific method does not claim
to produce any absolute truths - that's absoutely true!
:^) I leave more educated than I arrived.

Regards,
Tip

PS: as a special favor to you, I will never testify
that you have ever told the absolute truth ;^)

"Please note, Mr. Seedhouse, that I have no control over any
what ads appear in Stereophile. The "Chinese Wall" that
separates a magazine's advertising department from its
editorial staff also operates in the opposite direction. I
have no knowledge about the ads that appear in an issue of
Stereophile until I receive my printed copy.
John Atkinson"

At worst your knowledge of ad content is but one iissue old and a backward
perspective to confirm and see trends. While knowing can't be absolute
the categories and brands most likely to appear are knowable within a high
degree of probability. "Contro" cuts both ways from the editor's chair,
content which consistently contridicts marketing claims and manufactured
images would be the editorial feedback which also affects potential of
reupping on ad space. A tice clock now and again makes little difference
and adds a bit of ammo for critics, but wire etc. put in a supportable
light would soon sever it's connection with the mag.

normanstrong wrote:
"Stewart Pinkerton" wrote in message
...
On 18 Dec 2004 23:32:41 GMT,
wrote:

But what I fail to understand is how the statistics _know_ what
the device under test is? How, when testing loudspeakers for
example, a 95% probability of the results not being due to random
guessing can be taken as probably meaning there is a real sonic
difference, but in the case of amplifiers it cannot.

Yes, in your _opinion_, Mr. Nousaine, there is no reason for
amplifiers to sound different, but as has been pointed out before,
your opinion carries no special weight over anyone else's.

I can't speak for Tom, but there has been in existence for about six
years, a $5,000 prize awaiting anyone who can differentiate two
cables
in a level-matched DBT, in any system of their choice and with any
music of their choice. The bar has been set at 15 or more correct
out
of 20 trials, and that has not changed. Interestingly, despite many
claims of 'night and day' differences, there have been no
contenders.

After playing around with my calculator, I notice that you have a
50-50 chance of losing your $5000 after 32 people have taken the test.
You should collect $20 for the privilege of taking the test. Even
unlikely things happen every so often.

Norm Strong

It seems like the 95% confidence level is established at 15 out of 20
trials. So there is a 5% chance that someone can win $5K by sheer
guessing. Should we then set the entry fee to 5% of $5K, which is $250?
I'm sure that should not be a deterrent to those who are sure that there
is a difference .

Or we can lower the entry fee to $50 if the bar is set at 18 out of 20
trials.

How did you come up with $20?

On 21 Dec 2004 00:46:52 GMT, wrote:

...it is certainly true that JA makes a living for, among
other things, accepting and publishing advertisements for
products that I personally think can justifiably be called
"snake oil".

Please note, Mr. Seedhouse, that I have no control over any
what ads appear in Stereophile. The "Chinese Wall" that
separates a magazine's advertising department from its
editorial staff also operates in the opposite direction. I
have no knowledge about the ads that appear in an issue of
Stereophile until I receive my printed copy.

You might have no "control" but still have influence. Do you suggest
that if, for example, you objected strongly and in print to accepting
an advertisement from a particular supplier this would have no effect
whatsoever on whether or not that ad appeared?

But even so and accepting what you say above as perfectly true, the
words you have quoted from me are still, I think, also perfectly true.
Even if you have no control and no influence over adds it is still a
fact (or was last time I looked) that Stereophile publishes adds from
people that I personally think are purveyors of "snake oil", and it is
still a fact that you profit from their publication. After all you
don't edit the magazine for free, do you?

Not that am I suggesting that you should, or that there is something
wrong with you're getting paid for what you do.

And of course what I said above would also be true of my local
newspaper.

Ed

"chung" wrote in message
...
normanstrong wrote:
"Stewart Pinkerton" wrote in message
...
On 18 Dec 2004 23:32:41 GMT,
wrote:

But what I fail to understand is how the statistics _know_ what
the device under test is? How, when testing loudspeakers for
example, a 95% probability of the results not being due to
random
guessing can be taken as probably meaning there is a real sonic
difference, but in the case of amplifiers it cannot.

Yes, in your _opinion_, Mr. Nousaine, there is no reason for
amplifiers to sound different, but as has been pointed out
before,
your opinion carries no special weight over anyone else's.

I can't speak for Tom, but there has been in existence for about
six
years, a $5,000 prize awaiting anyone who can differentiate two
cables
in a level-matched DBT, in any system of their choice and with
any
music of their choice. The bar has been set at 15 or more correct
out
of 20 trials, and that has not changed. Interestingly, despite
many
claims of 'night and day' differences, there have been no
contenders.

After playing around with my calculator, I notice that you have a
50-50 chance of losing your $5000 after 32 people have taken the
test.
You should collect $20 for the privilege of taking the test. Even
unlikely things happen every so often.

Norm Strong

It seems like the 95% confidence level is established at 15 out of
20
trials. So there is a 5% chance that someone can win $5K by sheer
guessing. Should we then set the entry fee to 5% of $5K, which is
$250?
I'm sure that should not be a deterrent to those who are sure that
there
is a difference .

Or we can lower the entry fee to $50 if the bar is set at 18 out of
20
trials.

How did you come up with $20?

The probability of 15 correct out of 20 is 2.1%. IOW, the chances of
not doing that well are 97.9%. The p of not doing that well 32 times
is thus 0.979^32 = .507.

So how did I come up with $20. Simple. I dropped a zero in my haste
to post. :-)

Sorry,

Norm

In article , Stewart Pinkerton
wrote:

[from an earlier post in this thread]

No, you need to look up basic statistics. 18 correct out of twenty
'coin tosses' is *way* better than 90% probability of a detectable
difference.

[and now in a more recent one]

No. If you get 18 correct out of 20, there is a better than 99% chance
that there was something detectable.

Actually Mr. Pinkerton needs to look up basic statistics. Here he makes
the same error that Mr. Atkinson and Mr. Krueger frequently do.

The claim that getting 18 correct out of 20 means there is a better than
99% chance that there was something detectable is essentially:

(1)
IF someone gets 18 correct in 20 trials

THEN P[ there is something detectable ] .99 .

What is true is that:

(2)
IF someone is guessing (or flipping a fair coin)

THEN P[ at least 18 correct in 20 trials ] is about 0.000201, and P[
exactly 18 correct ] is about 0.000181.

(1) and (2) are NOT equivalent yet they are often confused, especially by
people with no mathematical and statistical training.

BTW unless you are a Bayesian you probably wouldn't even write something
like (1), as it is meaningless to a classical (frequentist) statistician.
For a frequentist the probability that someone was guessing is either 1 or
0, but he just dosn't know which of those it is.
[There are subjectivist/objectivist issues outside of audio. ;-) ]

If you toss a coin twenty times and get 15 heads, then that will happen on
average once every twenty times you try it.

If Mr. Pinkerton wants to bet that on average he'll get 15 heads in twenty
tosses once every twenty times he tries it, he may find lots of people
willing to bet against him.
The actual probability of exactly 15 heads in 20 tosses is .0148 (about
1/68) and the probability of at least 15 heads in 20 trials is 0.0207, or
1/48.

Maybe Mr. Pinkerton should learn some statistics. ;-)

In article , "normanstrong"
wrote:

"chung" wrote in message
...
normanstrong wrote:


After playing around with my calculator, I notice that you have a
50-50 chance of losing your $5000 after 32 people have taken the
test.

Close, but you have to watch round-off error.

x P[at least 1 winner in x runs of 20 trials]
--------------------------------------
32 .4879
33 .4985
34 .5088

It seems like the 95% confidence level is established at 15 out of
20 trials. So there is a 5% chance that someone can win $5K by sheer
guessing. Should we then set the entry fee to 5% of $5K, which is
$250?

But the probability of winning is not 5%.

The binomial distribution is discrete, so its natural significance tests
come only in certain sizes, e.g., 14/20 gives .0577 and 15/20 gives .0207
(actually .02069473).

Using 15/20 we get an expected value of
(.02069473)(5000) + (.97930527)(0) = $103.47
as an entry fee for a fair game.

BTW, there is a difference between a *significance level* of 5% and a
*confidence level* of 95%.

Or we can lower the entry fee to $50 if the bar is set at 18 out of
20 trials.

P[ 18 or more correct in 20 trials ] = .0002012253
so expectation for fair game is (.0002012253)(5000) = $1.006126

How did you come up with $20?

The probability of 15 correct out of 20 is 2.1%. IOW, the chances of
not doing that well are 97.9%. The p of not doing that well 32 times
is thus 0.979^32 = .507.

So how did I come up with $20. Simple. I dropped a zero in my haste
to post. :-)

????

In article , Chung wrote:


I don't think it is a case of misreading. And I don't think you
understand the principles of statistics yet. If you select correctly 18
times out of 20 times, then there is a very high probability (much more
than 90%) that you are not guessing and that there is some real
detectable difference.

Have they stopped teaching statistics in undergraduate engineering
curriculum these days?

If that's where people pick up the sort of misunderstandings that some
posters have of statistics, then maybe they should stop teaching
statistics in undergraduate engineering curricula. ;-)

Perhaps you could explain exactly how you get a numerical value (e.g.,
much more
than 90%) based solely on selecting correctly 18 times out of 20 times,
for the probability that you are not guessing and that there is some real
detectable difference?