Derek Atkins <[EMAIL PROTECTED]> wrote: > Were there really 750 Million Passengers flying through ATL?
No, 75 million. If you look at my message again I did correctly say 750,000 for the 1% false positive figure, although I did not type a comma to make it easier to read. > Therefore, a better question would be how many UNIQUE > assengers flew threw ATL, and then take 1% of that True, but to a first approximation most of the 200,000 average passengers per day in ATL will be unique individuals, so the false positive rate over the entire population is a good indicator of the effect of deploying the system in an airport. In any case, unless the individuals who repeatedly are falsely matched against the database stop travelling, they would increase the overall false postive rate by the same amount that repeat passengers who are not falsely matched decrease the overall rate. The more important number in these trials to ask about is the size of the database. A 1% false positive rate on a large population matched against a database of 5 faces is much worse than the same rate against a database of 500000. The article mentioned a watch list size of 3000, which seems like a reasonable size for comparison, but the article implies that there were different trials conducted for the study. Without referring to the original report I can't tell if the 1% FP rate was based on that trial or one with a different size database. Taking into account the imprecision inherent in a news article reporting on a large study, all it is safe to say is that when it says "only one subject in a 100" the article is saying "only" while presenting a really horrific scenario for the airport security people if this system is used to screen all the passengers. -- sidney --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
