AUTOMATIC OPTIMIZATION OF CONTENT ITEMS

Methods, systems, and apparatus include computer programs encoded on a computer-readable storage medium, including a system for providing content and that includes subsystems. An attribute inference subsystem analyzes content items and tags each content item with attributes that may affect performance and that are related to attribute types selected from a group comprising content concepts, format, included content, semantics or syntax. Attributes can be identified by the attribute inference subsystem or a sponsor of a respective content item. An analysis subsystem evaluates a log of served content items that have been tagged to identify salient attributes related to one or more performance metrics and inferences related to the identified salient attributes. An experiment subsystem automatically creates one or more experiments to substantiate the inferences related to the identified salient attributes. A processing subsystem delivers results based on substantiated inferences developed after evaluation of experimentation data derived by the experiment subsystem.