A method of compiling values that relate to aggregate data includes providing, from a data warehouse system and to a computer device, an output that causes a visual display of an aggregate data portion on the computer device. The aggregate data portion has been aggregated from selected data records in a data source system. There is received, at the data warehouse system and from the computer device, a user input indicating a request to compile values stored in a field of each of the selected data records. The method includes compiling, in the data warehouse system, the values stored in the field of each of the selected data records. The compiled values may be used to create a target group for a marketing campaign.