1. A method of predicting interest levels associated with publication and content item combinations, the method implemented by a server computing device communicatively coupled to at least one client computing device, the method comprising: determining a first interest level associated with a first combination including a first publication and a first set of keywords used for selecting a first content item for display in conjunction with the first publication, the first interest level representing a click-through-rate associated with the first content item and the first publication; determining a second interest level associated with a second combination including a second publication and a second set of keywords used for selecting a second content item for display in conjunction with the second publication, the second interest level representing a click-through-rate associated with the second content item and the second publication; identifying a first dependency that indicates a proportion of the first interest level attributable to the first set of keywords; identifying a second dependency that indicates a proportion of the first interest level attributable to a first provider of publications associated with the first publication; identifying a third dependency that indicates a proportion of the second interest level attributable to the second set of keywords; identifying a fourth dependency that indicates a proportion of the second interest level attributable to a second provider of publications associated with the second publication; and generating (i) a proposed combination of the first publication and one of the first set of keywords and the second set of keywords and (ii) a predicted interest level associated with the proposed combination, based on the first interest level, the second interest level, the first dependency, the second dependency, the third dependency, and the fourth dependency, wherein generating the predicted interest level comprises determining a predicted interest level associated with each combination of the first publication and one of the first set of keywords and the second set of keywords, and generating the proposed combination comprises identifying which combination of the first publication and one of the first set of keywords and the second set of keywords has a highest predicted interest level.