Abstract: Methods, and systems, including computer programs encoded on computer-readable storage mediums, including a method for providing to a user device a rule set specifying adjustments to be made by the user device to predicted performance measures of content items presented by the user device. The method includes receiving a content item request from a user device for content items, the user device being associated with a user device identifier; determining content items responsive to the content item request, each of the content items have a predicted performance measure; identifying a rule set specifying adjustments to be performed by the user device to the predicted performance measures of the determined content items in response to particular user interactions with the determined content items when presented on the user device; and providing the determined content items and the rule set to the user device in response to the content item request.