Postmortems of the 2010 Midterm Election Forecasts: A Post-Mortem on “Will the Republicans Retake the House in 2010?”

Abstract

A bare-bones, “economic performance” model of the number of seats won by the president's party in U.S. House of Representatives elections, estimated over the 1914–2008 period, yielded a point forecast of 227 seats for the Democrats, a net loss of 30 seats relative to what the party held at the start of the 111th Congress (if estimated with midterm elections only; 27 seats, if estimated with all elections). However, there was a great deal of uncertainty around that number, to the degree that there was “one chance in three or four that the Democrats [would] lose at least 40 seats,” enough to deprive them of a majority (Cuzán 2010a). Moreover, “the historical distribution of incumbent midterm losses” since 1914 suggested “that the odds of such an outcome occurring [were] around two in five,” so that “although the model forecasts lean against it, a change in party control cannot be dismissed tout court” (Cuzán 2010a, 640–41).