&gt; Confidence is simply how much confidence you have that the predicted class is correct.<p>If you mean correct among the number of output nodes, then we are talking about the same thing.  If you mean correct among all the possibilities to include those unknown to the NN, then I&#x27;d appreciate a link - because I&#x27;ve never seen that before and it sounds incredibly useful.<p>&gt; ...I don&#x27;t know of any simple test that will give you a 0 if you&#x27;re over-fitting and 1 if you&#x27;re not.<p>Neither do I, that is why I used all those weasel words - but I also don&#x27;t know of a neural network that wasn&#x27;t either being misused or being overfit that returned such results.  A simple example would be the 2 inputs for the xor test data, a hidden layer with enough nodes to memorize every permutation, and 2 output nodes - each representing the confidence for the potential result of the binary operation.