Presidential Vote Equation--July 31, 2008
The BEA revised the NIPA data back to 2005, and the revised data now show three strong ("good news") quarters---2006:1, 2007:2, and 2007:3---instead of only two before. There is now only one quarter of economic data not known before the election, namely 2008:3. Using the actual data through 2008:2 and the US model's current (July 31, 2008) forecast for 2008:3, the values of GROWTH, INFLATION, and GOODNEWS are 1.0 percent, 3.0 percent, and 3, respectively. These are close to the values used for the April 30, 2008, forecast, which were 1.5, 3.0, and 2, respectively. Given the current values, the predicted Republican vote share (of the two party vote) is now 48.5 percent rather than 47.8 percent before. The Republicans picked up a little because the extra good news quarter added more than the lower value of GROWTH took away.

It should be noted that the forecast of inflation for 2008:3 from the US Model is larger than the current consensus view and the forecast of real output growth for 2008:3 is also larger. It is possible on this website to enter your own values for the three economic variables and produce a prediction for VOTE. (Compute your own prediction for 2008 using the 2004 update.) For example, if you think the growth rate in 2008:3 will be lower than the US model's forecast, you can enter a smaller value for GROWTH than the default value of 1.0 percent. Similiarly, you can enter a smaller value for INFLATION if you think inflation in 2008:3 will be smaller than the US model is forecasting. At this stage, however, these adjustments are fairly minor because most of the economic data are already known. Remember that INFLATION is the average inflation rate over the entire 15 quarters before the election.