Ques 16-18 How to find Ein?

[vmathur87]

Sorry if my question is naive, but how do I find Ein for regular RBF? I got the weight vector w (of length k+1), but what do I do with it? I know I am missing something simple, but I just can't figure this out. Thanks for any help in advance!

[yaser]

Originally Posted by vmathur87

Sorry if my question is naive, but how do I find Ein for regular RBF? I got the weight vector w (of length k+1), but what do I do with it? I know I am missing something simple, but I just can't figure this out. Thanks for any help in advance!

You have the weights so you have the formula for the hypothesis that RBF is implementing. All you need to do is apply it to each input in the data set and check if the value it returns disagrees with the corresponding output. The fraction of training data points on which it disagrees will be .

[vmathur87]

Thanks, I understand that. But do you mean to apply the weights to each input according to the formula given on slide 14 of lecture 16? I think that since that formula was used to derive the weights (using phi), the weights would always satisfy it and the Ein will always be 0. Maybe this doesbn't make too much sene, but I am a little muddled up here.

[kkkkk]

Please see slide 19 of lecture 16 which shows h(x) for regular rbf with the bias b (not part of the summation, b is w0).

[vmathur87]

Thanks, I got it!

[alasdairj]

OK, I am a little confused. The RBF description does not mention a bias, but then it is introduced in slide 19 of lecture 16... how do we learn the bias?