A system and method for dynamically determining the demographic identity of an individual operating a set-top box, is disclosed which may include monitoring set top-box events for a plurality of set-top boxes, correlating set-top box events with demographic characteristics, applying with a computer inverse demographic matrix calculation techniques to determine probabilities for demographic characteristic and set-top box event dataset correlations without knowing individual-specific demographic information pertaining to the set-top box event dataset, ascribing demographic characteristic probabilities to each set-top box over time based on observed set-top box events and their relationship to such inverse demographic matrix probabilities, evaluating such ascribed demographic characteristic probabilities over time through statistical analysis, fining probabilities ascribed to demographic characteristics to statistically determine the most likely set of constant dataset possibilities for each set-top box, and fitting set-top box possibility sets to inverse demographic matrix probability sets for a set-top box event.