Embodiments of the invention relate to the graphical display of data at a summary level. In such embodiments, icons are used, where a visual representation of each of the icons represents a feature of underlying data. A user can select an icon in a summary data view to navigate to more detailed data associated with the icon. Embodiments of the invention also provide methods for calculating and using a student proficiency ranking index for use in comparing, aggregating, or otherwise processing heterogeneous test data.