1. A computer-implemented method for selecting a subset of a set of comments associated with a group of documents, the method comprising: accessing, at memory locations, the set of comments and a predetermined annotation probability distribution of annotations for another set of comments associated with another group of documents, wherein the annotation probability distribution specifies biases in the annotations for the other set of comments; and using a computer processor that is coupled to the memory location and programmed to select the subset: selecting the subset based on the annotation probability distribution and an objective function from a supervised-learning technique, wherein the objective function is optimized by maximizing an expression comprising the annotation probability distribution and the objective function.