 Using such information allowed Silver to come up with estimates of the vote preferences even in states for which there were few if any polls.For his general election projections for each state, in addition to relying on the available polls in a given state and "similar states," Silver estimated a "538 regression" using historical voting information along with demographic characteristics of the states to create an estimate that he treated as a separate poll (equivalent to the actually available polls from that state).This approach helped to stabilize his projections, because if there were few if any polls in a given state, the state forecast was largely determined by the 538 regression estimate.