Talk:False negative

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Mathematics

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signal detection[edit]

"The term false negative is also used when spam email is not detected as such but rather classified as non-spam email. A low number of false negatives is an indicator of the efficiency of spam filtering methods."

is that correct? maybe i'm missing something. but, a low number of false negatives doesn't mean anything unless you have a correspondingly low/good number of false positives.

if a spam filter simply labels ALL INCOMING MAIL as "spam", it will have zero false negatives. --very low, but very wrong.

it's the same thing as a lie detector that buzzes on every statement, therefore signalling 100% of lies, but...... also fale-alarming on every single truth.

of course i'm very tired, so i might be accidentally reversing the thing completely, but either way, the point still stands.

"condition"[edit]

I dont mind the term condition, but there are situations where that phrase would not be as apporpriate as singal. Condition also sounds like a disease or state of body instead of a state of reality. If there are better terms then signal or condition let me know, im checking some dictionary definitions of false negative/positive to find the best word. --ShaunMacPherson 10:56, 7 Aug 2004 (UTC)

The article on false negatives incorrectly defines a false negative rate as 1 minus the specificity. It is not. It is 1 minus the sensitivity.

Agreed. This is now fixed MDReid

Missed events vs. detected but incorrectly classified events[edit]

Maybe we could add that a false negative might be the result of: 1) detecting an event and incorrectly declaring it as positive; and 2) not detecting a positive event (e.g. a positive event was not even read) For example, a medical test in the lab can be very accurate and reliable, but somehow the reporting process or the bureaucracy around the test might be flawed: the positive outcome was not reported and for some reason the lab concludes the test was negative. For example, in computer security, a packet carrying a malware payload might have been missed completely by the intrusion detection system, but is is still a false negative.

False negative vs. false positive[edit]

There has been a simple error of juxtaposition here which I have corrected. False negative (the error of rejecting something that should have been accepted) is a type I error. False positive (the error of accepting something that should have been rejected) is a type II error. See, for example, Moulton, R.T., "Network Security", Datamation, Vol.29, No.7, (July 1983), pp.121-127:

The appropriate access control device may be difficult for the user to define. It must be capable of rejecting imposters while having a minimal rate of rejecting authorized users (Type I error). It must also have a high rate of accepting authorized users and a low rate of accepting imposters (Type II error).

I have also adjusted the redirections so that now has type I error to False negative; and Type II error to false positive. Once my piece on Four types of error is finished, and it will be finished very soon, the entire issue will be very plainLindsay658 08:07, 23 June 2006 (UTC)[reply]