Abstract: Systems, methods, devices, and techniques for improving the efficiency of selecting digital components to present in electronic documents and reducing latency in rendering digital components in electronic documents. In some implementations, a content distribution system uses predicted metrics for a set of candidate components to determine items to present in an electronic document responsive to a request. A metric prediction model can generate predicted metrics with the aid of a parameter prediction sub-model that predicts a value of a non-observable parameter associated with a request for a digital component.