Use an Aggregator

This example describes how to compare the average peak areas for two different sets of samples (for example, calibration samples and checkout samples, or samples with a name containing SampleA and samples with a name containing SampleB).

To prepare the variables:

1. Add the Compound Results table two times to the template.

2. Filter the tables according to the samples for which you want to obtain the average peak areas.

   To filter for the sample type

   Expression	Operation	Value	Description
   =Sample_Type	=	=1	The first table contains only calibration samples.
   =Sample_Type	=	=2	The second table contains only checkout samples.

3. In each table: Open the Column Properties dialog of the Area column, and save the value as a variable. Use the following settings:

   • Calculation Variables: Aggregator

   • Calculation Variable Name: For example, AreaAggregator1 in the first table, and AreaAggregator2 in the second table.

   • Category: [None]

   • Condition: [None]

To use the variables:

Underneath the two tables, create a text field with the following expression: =Avg(AreaAggregator1) - Avg(AreaAggregator2)

Instead of the Avg function, you can also apply the Sum, Stdev, Prsd, Min, Max, or Count function to the Aggregator variables.

Clear function If you create and use the Aggregator inside a composite group, use the Clear function at the end of the group. Add two hidden text fields with the following expressions: =Clear(AreaAggregator1) =Clear(AreaAggregator2) This clears all contents of the Aggregator, which ensures that the values are not mixed in subsequent group repetitions.