A bid strategy with a cost per activity (CPA) goal allows you to set a target CPA. You're instructing DoubleClick Search to manage your keywords so the target is reached. To reach the CPA target percentage, DoubleClick Search raises or lowers the bid based on how the actual CPA compares to the target CPA.
CPA target $
Enter the CPA target dollar amount in this field.
CPA conversion type
The option you select in this field determines how CPA is calculated:
You can combine a Position goal with a CPA goal to help your program meet multiple objectives. Use this combination if you're trying to meet a CPA objective, but you also want to ensure that the keyword never drops below a particular position or rank. For example, you have a CPA goal, but you also want to make sure the ads always appear on the first page of search results.