Abstract: Example demographic estimation systems disclosed herein include a feature generator to generate features from return path data reported from set-top boxes associated with return path data households; a neural network to process the features generated from the return path data to predict demographic classification probabilities for the return path data households, the neural network to be trained based on panel data reported from meters that monitor media devices associated with panelist households; a demographic assignment engine to assign one or more demographic categories to respective ones of the return path data households based on the predicted demographic classification probabilities; and a visitor assignment engine to assign virtual visitors to at least a subset of the respective ones of the return path data households based on the one or more demographic categories assigned to the respective ones of the return path data households.