> The "professional" definition looks like a "marketing numbers" > game...
It may well, but it's the only definition. Your metric is valid, but it needs a different term. The false positive rate is absolutely, undeniably a "quality or accuracy indicator," and has complete acceptance in research and analysis. One thing that may be frustrating you is that it's used when medical research frames a erroneously "positive" test result as relatively harmless, but an erroneous "negative" as bad--such as your "positive" test for monkeypox, when a person doesn't have it after further scrutiny, no big deal--in some senses, the opposite from spam analysis. Anti-spam vendors and pundits have long been mixing-and-matching willy-nilly from concepts like absence/presence of spamminess, positive/negative probability of non-spamminess, etc....in other words, we've probably all been misusing, or inconsistently using, scientific lingo from the get-go, and if "positive" itself is ambiguous, certainly so will be "false positive" and "false positive rate" be confusing. Back on the scientific note, your example of a 1/99,991 false positive rate being linked to 10 test positives in a monkeypox test would never pass muster in medicine if the data were not at or above some previously agreed-upon level of statistical significance (p1 < p2 =< .05), and it's unlikely that a disease that's only present in 9/100,000 of the population would be able to be tested using a sample size of only 100,000. The anti-spam world has not, however, unified on the specific parameters necessary to publish results using well-defined statistics terms. So you're correct in seeking the raw test results behind marketing claims; in general, anyone who won't provide raw test results on request is not trustworthy, and many such offenders are comfortably within the medicine and scientific establishments, both industrial and academic. Then, in the non-peer-reviewed world of which anti-spam is a part, you'd probably be astounded at how many over-the-counter testing kits, local-news surveys, weight-loss pills, and the like, generate false positives as often as true positives. Perhaps we should stick, rather, with neologisms such as "Ham" (though these are derided by many who think we already have our jargon down and should stick with it, a Catch-22). > The totally separate "false negative" evaluation is: of the 99,990 > decisions "this person doesn't have monkey pox", how many really did > have monkey pox (false negative)? FTR, the false negative rate is the percentage of those who are truly negative who tested as positive. That is, if the test missed 3 people, the false negative rate would be 3/12. -Sandy ------------------------------------ Sanford Whiteman, Chief Technologist Broadleaf Systems, a division of Cypress Integrated Systems, Inc. e-mail: [EMAIL PROTECTED] ------------------------------------ To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/
