Axes can be collapsed as well as rotated, in which case the data on the axis is aggregated according to the choice made on the ``Set next aggregation'' Ravel context menu. In the next figure, Price is chosen on the Data axis, and all other axes apart from Date are aggregated by the Sum function (the default aggregation method). The Ravel therefore outputs total sales by date.
![\includegraphics[width=\textwidth]{images/SmallBusinessAggregation}% WIDTH=527 HEIGHT=311](img269.png)
The available aggregations are: Sum, Product, Average, Minimum, Maximum, and Standard Deviation. The default setting is Sum. The other options can be set via the Context (right-mouse click) menu for Ravels.