Overview
When writing reports you will often have a need to summarise figures rather than displaying transaction level data (that is, returning individual transactions rather than a total or count). Aggregations are the method used to summarise fields. The aggregation functions available are Sum, Average, Min, Max, Count, and Count Distinct.
Sum of all values returned in the table. These sums may be split up by dimension fields to create sums for each category value. For example, the sum invoiced amount by each year. 

Average value of the items returned in the table. The average may be split up by dimension fields to create averages for each category value. For example, average age of customer by demographic. 

Minimum value returned in the table. These may be split up by dimension fields to find the minimum value for each category value. For example, the minimum rating per camp. 

Maximum value returned in the table. These may be split up by dimension fields to find the maximum value for each category value. For example, the maximum number of complaints by telephone operator. 

Count of the number of items returned in the table. These may be split up by dimension fields to find the number of items for each category value. For example, count the number of calls received by operator, by hour. 

Count of the number of Distinct items returned in the table. These may be split up by dimension fields to find the number of distinct items for each category value. For example, count the number of customers who called, by operator, by hour. 
Applying an Aggregation
To add and aggregation to a field, complete the following:
 Click on the field's drop down menu once it had been added to the report. There are two ways you can do this:
 Through the Columns/Rows list
 Through the Table Preview
 Through the Columns/Rows list
 Select the aggregation option from the list, then choose the aggregation you wish to apply.
 Your field should now have the aggregation applied to it, and the corresponding icon displayed in the Columns/Rows list of the Data step.
Changing or Removing an Aggregation
To change the aggregation applied to a field, or remove it, complete the following:
 Click on the field's drop down menu (using either of the options described above)
 Select the aggregation option from the list, then either choose an alternative aggregation, or None to remove the current aggregation