"Sidney Markowitz" <[EMAIL PROTECTED]> writes:

> > In addition, only one subject in 100 is falsely linked
> > to an image in the data base in the top systems.
> Wow, 99% accuracy for false positives! That means only a little more than
> 750000 people a year mistakenly detained for questioning in Atlanta
> HartsField Airport (ATL), and even fewer at the less busy airports (source
> Airports Council International, 10 Busiest Airports in US by Number of
> Passengers, 2001).

Were there really 750 Million Passengers flying through ATL???  That
number seems a bit high...

Also, I'm not convinced that multiple trials for a single individual
are independent.  Indeed, one could easily assume that multiple trials
for a single individual are highly correlated -- if the machine isn't
going to recognize the person on the first try it's highly unliklely
it will recognize the person on subsequent tries.  It's not like there
is a positive feedback mechanism.

Therefore, a better question would be how many UNIQUE passengers flew
threw ATL, and then take 1% of that for the number of false positives.
I think it's safe to assume that the 99% accuracy for false-positives
is over the population, not over the number of trials.

>  -- sidney markowitz


       Derek Atkins
       Computer and Internet Security Consultant
       [EMAIL PROTECTED]             www.ihtfp.com

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