Abstract: When an opportunity arises to present a content item to a user, an online system delivers a content item to a user according to a first content delivery strategy associated with the content item. For the impression of the content item to the user, the online system tracks attributes associated with the first content delivery strategy. In addition to tracking the attributes associated with the first content delivery strategy, the online system also tracks attributes associated with at least one other content delivery strategy (a second content delivery strategy). The attributes tracked for the second content delivery strategy are used to train a machine learning model for the second content delivery strategy. The model is used to deliver the content item or other items according to the second content delivery strategy.

Abstract: An online system generates predicted outcomes for a content distribution program that distributes content to users of the online system, the predicted outcome indicating a likelihood for the occurrence of an outcome of a content presentation. The online system transmits the one or more predicted outcomes to the third party system, and receives prediction improvement data from the third party system, the prediction improvement data indicating an adjustment to errors in the predicted outcomes based on a prediction by the third party system. The online system updates the properties of a content distribution program based on the prediction improvement data, the updated content distribution program causing the online system to generate new predicted outcomes based on the prediction improvement data in content presentation opportunities. The online system also transmits content to users of the online system based on the updated content distribution program.

Abstract: An online system receives explicit user data and explicit event data, and implicit user data and implicit event data from a third party system. The online system generates an implicit users/implicit events data feature, an explicit users/explicit events data feature, and an explicit users/implicit events data feature. The online system generates a prediction of the counterfactual rate based on the implicit users/implicit events data feature, the explicit users/explicit events data feature, and the explicit users/explicit events data feature, the counterfactual rate indicating the likelihood that target users matching certain characteristics caused an event to occur when the target are not been presented with content by the online system, the content configured to induce users to cause the event to occur. A combined prediction rate is presented to the third party system based on the counterfactual rate.

Abstract: An online system receives third party source data from a third party system including content feature vector entries and user feature vector entries, each content feature vector entry describing an corresponding user of the third party system, each component in each user feature vector related to a characteristic of the corresponding user. The online system generates a combination score for a target user and a selected content item by computing a combination of the content feature vector entry associated with the selected content item and the user feature vector entry associated with the target user using a combining function, the combination score indicating an estimated increase in value for the third party system when the target user is presented with the selected content item.

Abstract: An online system, such as a social networking system, generates shared models for one or more clusters of categories. A shared model for a cluster is common to the categories assigned to the cluster. In this manner, the shared models are specific to the group of categories (e.g., selected content providers) in each cluster while requiring a reasonable computational complexity for the online system. The categories are clustered based on the performance of a model specific to a category on data for other categories.

Abstract: An online system optimizes selection content items for a user based on total value of presenting a selected content item, rather than discrete actions with the content item. To account for the total value of presenting a content item, the online system receives information from a third party system associated with the content item identifying actions by users captured by the third party system and values associated with the identified actions. The online system matches the identified actions with presentations of the content item to various users by identifying users of the online system corresponding to information identifying users received from the third party system and retrieves information describing presentation of content items to the information identifying presentation of content items. Based on historical actions and presentations of a content item, the online system obtains a model determining value of presenting a content item for use in selecting content.

Abstract: An online system manages a set of custom features for a third party system stored in user profiles. The online system accesses predictors for the third party system based on the set of custom features for the third party system, the predictors generating predictions for users to the third party system based on the custom features of a lifetime expected incremental value to the third party system from presenting the sponsored content item to the target user. The online system receives from the third party system, data elements for a target user, the data elements related to the actions performed by the target user. The online system extracts custom features from the data elements based on a custom feature definition associated with the third party system. The online system determines a value score for the target user based on the extracted custom features for the target user using the predictors.

Abstract: An online system identifies seed users of high value to a sponsored content provider. Characteristics of the seed users are identified, and additional users having a threshold measure of similarity to the seed users are identified based on the characteristics. A score is determined for each of the additional users based on the measure of similarity. The seed users are placed in an initial tier of a tiered set of users for the sponsored content, and the additional users are placed in additional tiers of the tiered set of users based upon the determined scores such that each additional tier includes those users of the additional users having a specified range of determined scores, the tiers of the tiered set of users ranked according to the determined scores of users within each tier.