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Tyler Takes An IMAX Hit



 
 
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  #21  
Old March 1st 05, 09:34 PM
Kurgan Gringioni
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Robert Chung wrote:
Kurgan Gringioni wrote:
Then those two get tested again. They both test positive *again*.

The odds of that happening are 250^4


You're assuming independence.





Dumbass -

Let's say that it's not, that one false positive test will always yield
a second positive on the B sample. Then the odds are one in 499 that it
TH's roomate will also test positive.

That 1 in 499 chance goes way, way up, however, when one considers that
*no one else* had a "false positive". I had a probability class a long
time ago and don't remember how to calculate it.

Someone who has a better brain than I step in here. Regardless, it's a
big number - something on the order of at least 10,000 to 1(very, very
conservatively).


thanks,

K. Gringioni.

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  #22  
Old March 1st 05, 09:49 PM
Robert Chung
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Kurgan Gringioni wrote:
Robert Chung wrote:
Kurgan Gringioni wrote:
Then those two get tested again. They both test positive *again*.

The odds of that happening are 250^4


You're assuming independence.


Dumbass -

Let's say that it's not, that one false positive test will always yield
a second positive on the B sample. Then the odds are one in 499 that it
TH's roomate will also test positive.

That 1 in 499 chance goes way, way up, however, when one considers that
*no one else* had a "false positive".


You're still assuming independence. This is exactly why the entire chain
of events has to be vetted. That was not done.

And, anticipating your question, I remind you of this:
http://groups-beta.google.com/group/...c35a0e1644d31c


  #23  
Old March 1st 05, 10:03 PM
Kurgan Gringioni
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Robert Chung wrote:
Kurgan Gringioni wrote:
Robert Chung wrote:
Kurgan Gringioni wrote:
Then those two get tested again. They both test positive *again*.

The odds of that happening are 250^4

You're assuming independence.


Dumbass -

Let's say that it's not, that one false positive test will always

yield
a second positive on the B sample. Then the odds are one in 499

that it
TH's roomate will also test positive.

That 1 in 499 chance goes way, way up, however, when one considers

that
*no one else* had a "false positive".


You're still assuming independence. This is exactly why the entire

chain
of events has to be vetted. That was not done.

And, anticipating your question, I remind you of this:

http://groups-beta.google.com/group/...c35a0e1644d31c



Dumbass -

How would Hamilton's test be dependent upon Perez's test?

thanks,

K. Gringioni.

  #24  
Old March 1st 05, 10:49 PM
Robert Chung
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Kurgan Gringioni wrote:
How would Hamilton's test be dependent upon Perez's test?


I didn't say that Hamilton's test is dependent on Perez's. I think it
likely that they're both dependent on the same systematic things.


  #25  
Old March 2nd 05, 04:37 AM
Tom Kunich
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"Robert Chung" wrote in message
...
Kurgan Gringioni wrote:
Robert Chung wrote:
Kurgan Gringioni wrote:
Then those two get tested again. They both test positive *again*.

The odds of that happening are 250^4

You're assuming independence.


Dumbass -

Let's say that it's not, that one false positive test will always yield
a second positive on the B sample. Then the odds are one in 499 that it
TH's roomate will also test positive.

That 1 in 499 chance goes way, way up, however, when one considers that
*no one else* had a "false positive".


You're still assuming independence. This is exactly why the entire chain
of events has to be vetted. That was not done.

And, anticipating your question, I remind you of this:
http://groups-beta.google.com/group/...c35a0e1644d31c


Robert, you're wasting your time arguing with Henry.


  #26  
Old March 2nd 05, 05:20 AM
Kurgan Gringioni
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Robert Chung wrote:
Kurgan Gringioni wrote:
How would Hamilton's test be dependent upon Perez's test?


I didn't say that Hamilton's test is dependent on Perez's. I think it
likely that they're both dependent on the same systematic things.




Dumbass -

Such as?

  #27  
Old March 2nd 05, 07:50 AM
Robert Chung
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Kurgan Gringioni wrote:
Such as?


Well, the obvious one is the one you're thinking of: that there was an
organized blood doping program. That's the one I lean towards, too. But,
remember, I get paid high in the three figures to worry about non-obvious
sources of systematic bias. That's part of what goes into proper vetting.


  #28  
Old March 2nd 05, 08:29 AM
Kurgan Gringioni
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Robert Chung wrote:
Kurgan Gringioni wrote:
Such as?


Well, the obvious one is the one you're thinking of: that there was

an
organized blood doping program. That's the one I lean towards, too.

But,
remember, I get paid high in the three figures to worry about

non-obvious
sources of systematic bias. That's part of what goes into proper

vetting.




Dumbass -

Seriously, what's a potential systemic bias in this case? I'm curious
what that may be.

thanks,

K. Gringioni.

  #29  
Old March 2nd 05, 10:35 AM
Robert Chung
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Kurgan Gringioni wrote:
Seriously, what's a potential systemic bias in this case? I'm curious
what that may be.


I emphasize that I don't know about this particular case but, in other
particular cases I've examined, systematic bias can arise because tests
were done in the same place by the same people with the same equipment.
This type of bias sometimes happens when there are a very limited number
of places where something is performed, or a limited number of examiners
who were all trained in the same place. Sometimes people see what they
expect to see (we could name some rbr'ers who fall into that category);
sometimes this happens innocently. Here's a kinda innocent way that things
can get biased: suppose, for example, 1) blood doping is pretty evenly
spread across the peloton; 2) experts at the technique are better at
recognizing blood doping than novices; and 3) when a case happens to be
sensitive it gets shunted up to an expert (this appears to be what
happened at the Olympics, and Dick Pound suggested that Hamilton's Vuelta
tests were scrutinized exactly because of the Oly results). Now suppose
samples from teammates of the suspected blood doper are considered to be
sensitive, and thus also get shunted to experts (it needn't be the same
expert, just to another expert who has a higher detection rate than a
novice). You would tend to see more doping than the overall rate based on
the experts' analyses, but you'd also see less doping than the overall
rate based on the novices' analyses.

I think it probable that Hamilton blood doped. I think it probable that
Perez blood doped. But I have no way of evaluating exactly how probable
since the test hasn't been properly vetted, and I wouldn't build on the
fact that only two people out those tested so far have been announced as
positive.

And, as for the A and B samples on each rider, they are done to eliminate
random error in testing, not systematic error.

Since Magilla claims to have seen the evidence, I'm hoping he'll tell us
the proportion of foreign cells that were detected in Hamilton's blood in
the Olympics A sample, the Vuelta A sample, and the Vuelta B sample. Two
samples taken from the same person at the same time, like the Vuelta A and
B samples, would give a very rough (n=2) idea of the precision of the
test. In conjunction with a sample taken at a different point in time,
like the Oly A sample, they might be able to give a rough idea of how much
doping occurred.

I think both sides in the dispute already know all of this.


  #30  
Old March 2nd 05, 05:41 PM
MagillaGorilla
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Kurgan Gringioni wrote:

Ewoud Dronkert wrote:

On Tue, 01 Mar 2005 15:48:16 GMT, B Lafferty wrote:

Don't forget Santi Perez's two positives. If they're all false


positives,

that makes five from two guys on one team. What are the odds?


We don't know, because there is nothing published on false positive


(or

false negative for that matter) rates for this test.





Let's say that all the tests are false positives.

What are the odds that the *only two* riders to get the false positive
are teamates and roomates?

Let's say 500 riders were tested. Two false positives make the rate 1
in 250.

Then those two get tested again. They both test positive *again*.

The odds of that happening are 250^4 = 3,906,250,000

about one in 4 billion. Then factor in the fact that they're roomates.
Multiply the 4 billion by 499.

1 in 2 trillion.

Poor Tugboat.



K. Gringioni.


Ahh. nope..the false positive rate is nothing of that magnitude if it's
linked to specific types of anitgens that only Perez and Hamilton have
in their blood.

They would always test positive.

Magilla

 




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