How to convert the output of an artificial neural network into probabilities?

Question

I\'ve read about neural network a little while ago and I understand how an ANN (especially a multilayer perceptron that learns via backpropagation) can learn to classify an

Answer 1

When using ANN for 2-class classification and logistic sigmoid activation function is used in the output layer, the output values could be interpreted as probabilities.

So if you choosing between 2 classes, you train using 1-of-C encoding, where 2 ANN outputs will have training values (1,0) and (0,1) for each of classes respectively.

To get probability of first class in percent, just multiply first ANN output to 100. To get probability of other class use the second output.

This could be generalized for multi-class classification using softmax activation function.

You can read more, including proofs of probabilistic interpretation here:

[1] Bishop, Christopher M. Neural networks for pattern recognition. Oxford university press, 1995.