Abstract: Methods and apparatus for calculating audience estimations are disclosed. An example method includes identifying a subset of stored viewership data and allocating an observation array having a first-dimension index, each indicie of the index associated with one time-period of at least one household datapoint in the subset of stored viewership data. Additionally, the example method includes transferring the identified subset to the observation array, building an extensible markup language (XML) file based on at least one detected characteristic in the observation array, and generating a graphical user interface (GUI) based on the XML file for use with at least one query selection associated with the at least one detected characteristic.