15. A non-transitory computer-readable storage medium encoded with instructions for controlling a computing device to calculate a bid amount for a keyword, by a method comprising: collecting conversion information for the keyword indicating financial benefit resulting from users selecting advertisements displayed with content that relates to the keyword, the financial benefit being organized into categories relating to sessions initiated by the selecting of the advertisements; determining a category-specific advertising expense factor for each category; calculating a category-specific product for each category, the category-specific product calculated by multiplying the financial benefit for the category by the category-specific advertising expense factor determined for the category; and generating a bid amount for the keyword based at least in part on a quotient of an aggregation of the category-specific products divided by number of sessions with financial benefit multiplied by a forecast conversion comprising a predicted percentage of clickthroughs associated with the keyword that result in financial benefit.
15. A non-transitory computer-readable storage medium encoded with instructions for controlling a computing device to calculate a bid amount for a keyword, by a method comprising: collecting conversion information for the keyword indicating financial benefit resulting from users selecting advertisements displayed with content that relates to the keyword, the financial benefit being organized into categories relating to sessions initiated by the selecting of the advertisements; determining a category-specific advertising expense factor for each category; calculating a category-specific product for each category, the category-specific product calculated by multiplying the financial benefit for the category by the category-specific advertising expense factor determined for the category; and generating a bid amount for the keyword based at least in part on a quotient of an aggregation of the category-specific products divided by number of sessions with financial benefit multiplied by a forecast conversion comprising a predicted percentage of clickthroughs associated with the keyword that result in financial benefit. 19. The non-transitory computer-readable storage medium of claim 15 wherein the generating of the bid amount includes multiplying the product by a category-specific forecast conversion rate before aggregating the products.