"Gary Drescher" wrote in message
...
"Chip Jones" wrote in message
k.net...
The method madated by the FAA ala a DOT 49 CFR Part 40 random urine
drug
test is called a GC/MS drug test. GC/MS drug testing has virtually *no*
false positives...

You can read all about it he
http://www.aviationmedicine.com/drugtest.htm

Nothing at that web page states that the test has a low false-positive
rate.

The false-positive rate isn't even inherent in a test itself. Specificity
is
an inherent property of a test--but even an excellent test with very high
specificity can still have an arbitrarily high false-positive rate if
applied to a population in which positive examples are sufficiently rare.
(The web page says nothing about the test's specificity either, by the
way.)

This is an issue that I can neither defend or attack, because I can't
quantify in my mind what an "arbitrarily high" false positive rate would be
in a test group like commercial aviators, where positive examples are, I
agree, very rare. To me, it is sufficient that GC/MS testing is very
accurate at detection and errs on the side of the person being tested (see
the false positive rate in the link below from a study from NIDA comparing
self reporting to GC/MS testing, which mentions the false-positive rate of
the GC/MS test across the spectrum).


Do you have support elsewhere for your "virtually no false positives"
claim?



Here are a few links:

Here's one from NIDA, where the false positive rate in GC/MS drug testing
for THC was 0.3 to 3.1%, and this was before any MRO action as per the DOT
CFR.

http://www.drugabuse.gov/pdf/monogra...6_Harrison.pdf

Here are some on the accuracy of GC/MS testing from some "how to beat the
test" camps. The first one says:

"Gas Chromatography Mass Spectrometry (GC-MS)
GC/MS is the most precise method of testing, it is so precise that
guidelines set by NIDA (National Institute on Drug Abuse) require positive
immunoassay (emit ), and gas chromatography tests be confirmed by a GC-MS
test. Only the Federal Government is required to follow these guidelines and
unfortunately most companies due not follow these guidelines. In other words
should you test positive falsely the GC-MS will confirm that you are not a
drug user, however the odds your tester confirms positive tests with GC-MS
are miniscule (why? It is expensive)."

http://www.streetdrugtruth.com/testing/testtypes.php4

And some more from pro-drug, anti-test groups on GC/MS testing accuracy:

http://cocaine.org/drugtestfaq/index.html

http://www.neonjoint.com/passing_a_d..._accuracy.html

http://www.ushealthtests.com/dtbasics.htm

http://www.onlinepot.org/misc/****tests.htm


Chip, ZTL