Dashboard allows you to group dimension values and display summaries for entire groups rather than individual values. You can arrange dimension values in groups of different sizes by specifying the appropriate group interval. For instance, date-time values can be grouped by year, month, quarter, etc.
Note that custom grouping is not supported in OLAP mode.
To specify a group interval in the Designer, invoke the data item menu and select the desired group interval. Less common group intervals are organized in the More submenus.