Abstract: Methods and systems for determining advertisement placements are described herein. The method includes retrieving a matrix of access time values, wherein each row is associated with a respective user, each column is associated with a respective media asset, and each access time value represents a length of time for which a respective user accessed a respective media source. The method includes identifying media sources accessed by a user, creating combinations of the identified media sources, and determining a minimum access value associated with each combination of the identified media sources. The method further includes creating an overlap value by adding the determined minimum access values to create an overlap value associated with each combination and selecting, based on the overlap value, a subset of a plurality of advertisement placement spots.