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Detecting unknown class in a bayes classifier

If you have a bayes classifier trained for a set of classes, how to detect if the output is significant enough to choose a class? It would be useful for detecting samples wich can't be asigned to a class. I have tried testing if the class probability is above mean+2*stddev of the probabilities of all the clases, but I don't think it will be robust.

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piotr Avatar asked Mar 09 '10 10:03

piotr


1 Answers

You could consider log-likelihood ratios. Consider R(C) = log(P(C|D)/P(~C| D), where C is the class, D are the features. Then you probably want to ensure that R(C) is greater than some positive amount.

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Il-Bhima Avatar answered Sep 28 '22 08:09

Il-Bhima