Methods are provided for navigation user interface mechanisms. In one embodiment, a directed summary of (i) what caused the value of a selected cell within a tabular view of data; or (ii) context into which the value of the selected cell fits as part of a larger overall picture is provided by displaying at least a partial hierarchy of child/parent views relating to the value of the selected cell, then the end user may navigate to a particular level of detail within the hierarchy of preaggregated data that is desired by selecting an appropriate child/parent view. In another embodiment, period queries are specified with reference to a dialog displaying a calendar view from which date groups to be compared may be selected. The dialog receives information identifying a period associated with each date group to be compared. The periods can be either asymmetrical or symmetrical with respect to each other.