15. The one or more computer-storage media devices of claim 10 , wherein the machine-learning model normalizes scores from contextual signal providers indicating a relevancy or an importance of each of the user-specific features.
15. The one or more computer-storage media devices of claim 10 , wherein the machine-learning model normalizes scores from contextual signal providers indicating a relevancy or an importance of each of the user-specific features. 16. The one or more computer-storage media devices of claim 15 , further comprising adjusting the normalized scores based on one or more of, a level of trustworthiness associated with a contextual signal provider that provided a particular user-specific feature, or a position bias effect that indicates an effect of positioning a particular document in a certain position.