AVGDIFF

Returns a number that represents the average difference between each of a child records of the parent.

AVGDIFF ( <field_name> [, <filter_query>] )

field_name: The numeric field to base the calculation on.
filter_query: A query string representing the domain of records to include.

Example: create field on the CUSTOMER table that returns, for each customer, the average difference in days between product purchases where the product code is B.

AVGDIFF( [PRODUCT.PRODUCT_PURCHASE_DATE] , [PRODUCT.PRODUCT_CODE] = "B")