Re: BBC **LIES** About HIV TESTS

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"Alex" in news:[EMAIL PROTECTED] :
> Wolfgang wrote:
> > "Alex" in news:[EMAIL PROTECTED] :

> > > 3) HIV Screening in a Military Blood Transfusion Centers
> > > This is Italian data from the general population (blood donors).
> > > http://www.certi.org/CMA/newsletter/v03n01.pdf
> > >
> > > Table II
> > >
> > > Number of dontations: 25,562
> > > Number of blood donations ELISA positive: 31
> > > Number of blood donations after confirmation test: 2
> > >
> > > This means that of 25,562 people tested with a single ELISA,
> > > 31 tested positive, and after further testing, only 2 *remained*
> > > positive.
> > > This means that in the field, ELISA had a ppv (positive predictive
> > > value) of 2/31 or 6.45%.
> >
> > This means that there are  (31 - 2) / 25,562 = 0.11%  false
> > positives.
> >
> > Only  2 / 25,562 = 0.008%  turned out to be HIV+.
> >
> > It IS relevant whether <0.008%> or <0.008% + 0.11%>, but it is
> > totally irrelevant whether <around 20%> or <around 20% + 0.11%>.

> The question has always been how many of the people
> who test positive on their first ELISA remain positive after
> further testing.
>
> The reason this is relevant, is because the "30%" number
> you go on to quote, is based on these single ELISAs.
>
> So it is irrelevant that the majority of the population in Italy
> doesn't test positive on ELISA. What is important is that
> 93.55% who do, DO NOT REMAIN POSITIVE AFTER
> FURTHER TESTING.

No, your figure of 93.55% is a completely meaningless number.

Let us test again the 25,560 Italians who are HIV-negative.
We will again get around 30 false positives. So we could
get for instance this result:

 Number of dontations: 25,560
 Number of blood donations ELISA positive: 29 (or 25, or 33)
 Number of blood donations after confirmation test: 0
 Percentage of non-confirmation: 29/29 = 100.0%

In this case not a single person remains positive after
further testing and your 93.55%-figure becomes 100%.

If we add 1000 HIV+ persons to the above 25,560 HIV-
negative persons, we get something like this:

 Number of dontations: 26,560
 Number of blood donations ELISA positive: 1029
 Number of blood donations after confirmation test: 1000
 Percentage of non-confirmation: 29/1029 = 2.8%


Your example actually is strong evidence for the contrary
your are claiming, namely it is evidence for a very low
percentage of false positives and therefore for the high
quality of such tests (at least in Italy): 25,531 out of
25,560, i.e. 99.98% have not resulted in false positives!


Cheers, Wolfgang


Why do "skeptics" believe in disinformation?
(was: AIDS Claims 650,000 in Zambia in 1996-1999):
http://groups.google.com/[EMAIL PROTECTED]