Systems and methods are described for determining and displaying optimal associations of data items. Data items may include media content such as television programs, and may be associated with advertisements to be displayed during content consumption. A tool may process data regarding segments of viewers that have common characteristics, and further process data regarding viewers of particular data items, to identify degrees of association between individual segments of viewers and particular data items. The degrees of association between a particular data item and multiple segments of viewers, or between multiple data items and a particular segment of viewers, may be displayed in a user interface that identifies optimal associations between data items and advertisements based on the viewer segments having high degrees of association with the data item.