The first computer prediction of a U.S. Presidential election was by a UNIVAC I computer used by CBS News on election night 1952. At 9:15 pm, with only 3.4 million of the eventual 61.8 million popular votes counted, the UNIVAC predicted 43 states and 438 electoral college votes for Dwight Eisenhower, and 5 states and 93 electoral votes for Adlai Stevenson. The actual results were 39 states and 442 electoral votes for Eisenhower. The popular vote was also within 3.5%. It proved to be a success for both UNIVAC and CBS.
What inputs and algorithms were used by the UNIVAC to predict the election? Was this merely a ratio of the votes counted at the time, or was there a more sophisticated mathematical model?