5. The method of claim 1 wherein training the model comprises: training a first model using the obtained presentation bias features to predict a click through rate based on input comprising the one or more presentation bias features; and training a second model using the obtained relevancy features to predict a click through rate based on input comprising the one or more relevancy features.
5. The method of claim 1 wherein training the model comprises: training a first model using the obtained presentation bias features to predict a click through rate based on input comprising the one or more presentation bias features; and training a second model using the obtained relevancy features to predict a click through rate based on input comprising the one or more relevancy features. 7. The method of claim 5 wherein the predicted click through rate for the particular second search result is a ratio of the respective predictive outputs of the first and second models.