1. A processor-based dialog system comprising: a central processing unit; a classifier circuit coupled to the central processing unit and configured to generate a plurality of predictions on a dialog act corresponding to an utterance received at an input; and a decision circuit coupled to the central processing unit and configured to generate a plurality of probabilities each of which corresponds to a prediction, dynamically select a set of predictions from the plurality of predictions, and classify the utterance according to an accumulated probability of the set of predictions, wherein the accumulated probability is an accumulated probability of variable n-best outputs, wherein the value n is a non-fixed integer value that is determined dynamically based on a classifier distribution of the utterance.