[R] Statistical significance of a classifier

From: Martin C. Martin <martin_at_metahuman.org>
Date: Sat 06 Aug 2005 - 05:58:39 EST


Hi,

I have a bunch of data points x from two classes A & B, and I'm creating a classifier. So I have a function f(x) which estimates the probability that x is in class A. (I have an equal number of examples of each, so p(class) = 0.5.)

One way of seeing how well this does is to compute the error rate on the test set, i.e. if f(x)>0.5 call it A, and see how many times I misclassify an item. That's what MASS does. But we should be able to do better: misclassifying should be more of a problem if the regression is confident then if it isn't.

How can I show that my f(x) = P(x is in class A) does better than chance?

Thanks,
Martin



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