Patent ID: 8694632

Claim:
A computer-implemented method performed by a data processing apparatus, comprising: for each of a plurality of requests for content items, each request received from a user device for an expandable content item to be displayed in a content item environment on a resource and specifying a resource address of the resource: identifying, from one or more predicted expansion directions, a predicted expansion direction for the content item environment based at least in part on the resource address, the predicted expansion direction specifying a predicted direction for expansion of the content item environment displayed on the resource based at least in part on a display configuration of the resource; generating a serving data log entry for the request specifying the predicted expansion direction and a unique identifier for the request; providing to the user device an expandable content item having the predicted expansion direction and response data specifying the unique identifier; receiving reporting messages from the user devices for the respective unique identifiers specifying the display configurations of the respective resources and display configurations of content item environments on the respective resources in which the respective expandable content items were displayed; determining pairs of serving data log entries and reporting messages based on the unique identifiers, each of the pairs being a pair of a serving data entry and a reporting message having a matching unique identifier; and for each pair, determining an accuracy measure for the respective predicted expansion direction based at least in part on a comparison of the respective predicted expansion direction and the display configurations of the respective resource and content item environment, the accuracy measure representing an accuracy of the respective predicted expansion direction being a match for the respective resource and content item environment.