Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for optimizing digital component transmission. A data structure stores session data for a user session. An encoder accesses the session data, encodes at least a portion of the online activities by representing different online activities with different symbols, and generates an encoded session string that includes multiple different symbols representing an order of occurrence of the different online activities. One or more servers classify the user session to a positive session classification or a negative session classification based on a classification score for the encoded session string, aggregates the classification of the user session with other classifications of other user sessions that have a same session string as the encoded session string, and adjusts distribution of digital components to client devices based on the aggregated classifications.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for optimizing digital component transmission. A data structure stores session data for a user session. An encoder accesses the session data, encodes at least a portion of the online activities by representing different online activities with different symbols, and generates an encoded session string that includes multiple different symbols representing an order of occurrence of the different online activities. One or more servers classify the user session to a positive session classification or a negative session classification based on a classification score for the encoded session string, aggregates the classification of the user session with other classifications of other user sessions that have a same session string as the encoded session string, and adjusts distribution of digital components to client devices based on the aggregated classifications.