House 2022

Post Mortem for the 2022 Election: November 23, 2022

As discussed below, the final ex ante prediction for the 2022 House two-party vote was 46.6 percent for the Democrats. The actual looks like it will be about 48.4 percent, for an error of 1.8 percentage points. This is less than one standard error. I have written a blog explaining the prediction, Did the Republicans Underperform in 2022?.

Background

The equation used to predict the Democratic share of the two-party House vote for 2022 is equation 3a in Table 2 in
Presidential and Congressional Vote-Share Equations: November 2018 Update.
The following discussion assumes that the paper,
Presidential and Congressional Vote-Share Equations, American Journal of Political Science, January 2009, 55-72
has been read. You can compute your own vote prediction using your own assumptions about the economy by clicking:
Compute your own prediction for 2022.

Economic Values and Vote Prediction: October 27, 2022

All the economic data are now available to allow the final prediction of the two-party House vote share. The final value of Pcc is 6.56 percent, and the number of strong growth quarters is 3, so Zcc = (15/7)x3 = 6.429. These values result in a predicted vote share for the Democrats of 46.62. This prediction is essentially the same as the one below dated July 28, 2022. The US model at that time predicted that 2022.3 would not be a strong growth quarter, which was correct. It predicted an inflation rate in 2022.3 of 4.7 percent. The actual value was 4.06 percent, and this difference has a very small effect on Pcc.

The following repeats the calculations below dated October 29, 2021, for the final data:

48.89    Constant term
-3.14    Coefficient estimate of I, the party dummy. This is the estimated 
         (negative) effect for the incumbent party in the White House.
 1.14     0.725*(Vc-2 - 50) =  0.725*(51.57 - 50).  House incumbency effect.
-0.49    -0.214*(Vp-2 - 50) = -0.214*(52.27 - 50).  Estimated effect from the
          size of the presidential vote share in the last election (balance effect). 

46.40   TOTAL so far

-2.95    -0.449*Pcc.  Pcc is 6.56.  Negative inflation effect.
 3.17     0.493*Zcc.  3 strong growth quarters, 2021.1, 2021.2, and 2021.4, 
                      so Zcc = (15/7)*3 = 6.429. 

46.62   PREDICTED VOTE SHARE FOR DEMOCRATS

The negative inflation effect almost exactly offsets the positive output effect.

Economic Assumptions and Vote Prediction: July 28, 2022

In the October discussion below Pcc was taken to be 6.0 and the number of strong growth quarters was taken to be 5. Data are now available for the four quarters of 2021 and for the first two quarters of 2022. The inflation rate for these six quarters is 6.6 percent at an annual rate, and there are 3 strong growth quarters. The current US Model forecast (July 28, 2022) has an inflation rate of 4.7 percent at an annual rate in 2022.3, and 2022.3 is not predicted to be a strong growth quarter. This gives overall an inflation rate (Pcc) of 6.4 percent. There are 3 strong growth quarters, so Zcc = (15/7)X3 = 6.429. Using these values, the predicted vote share for the Democrats is 46.70, which compares to 48.99 in October. The smaller predicted vote share for the Democrats is due to two fewer strong growth quarters and slightly higher inflation.

Economic Assumptions and Vote Prediction: April 30, 2022

In the October discussion below Pcc was taken to be 6.0 and the number of strong growth quarters was taken to be 5. Data are now available for the four quarters of 2021 and for the first quarter of 2022. The inflation rate for these five quarters is 6.2 percent at an annual rate, and there are 3 strong growth quarters. The current US Model forecast (April 30, 2022) has an inflation rate of 5.6 percent at an annual rate in 2022.2 and 2022.3, and both quarters are predicted to be strong growth quarters. This gives overall an inflation rate (Pcc) of 6.0 percent and 5 strong growth quarters, exactly what was used for the October 29, 2021, forecast. So the predicted vote share for the Democrats is the same at 48.99. This prediction is lower than the 50.31 percent for the January 27, 2022, prediction because inflation is higher and there is one less strong growth quarter.

Economic Assumptions and Vote Prediction: January 27, 2022

In the October discussion below Pcc was taken to be 6.0 and the number of strong growth quarters was taken to be 5. Data are now available for the four quarters of 2021. The inflation rate for the year is 5.7 percent, and there are 3 strong growth quarters. The current US Model forecast (January 27, 2022) has an inflation rate of 5.1 percent at an annual rate in the first three quarters of 2022, and all three quarters are predicted to be strong growth quarters. This gives overall an inflation rate (Pcc) of 5.4 percent and 6 strong growth quarters, so Zcc = (15/7)X6 = 12.857. Using these values, the predicted vote share for the Democrats is 50.31, which compares to 48.99 in October. The difference is due to one more strong growth quarter and slightly lower inflation.

Economic Assumptions and Vote Prediction: October 29, 2021

The two economic variables in the equation, using the notation in Table 1 in the above November 2018 update, are

Pcc = the growth rate of the GDP deflator in the first 7 quarters of the Biden administration, 2021:1-2022:3, at an annual rate,

and

Zcc = 15/7 times the number of quarters in the first 7 quarters of the Biden administration in which the growth rate of real per capita GDP is greater than 3.2 percent at an annual rate.

As of this writing data are available for the first three quarters of the Biden administration. For these three quarters the growth rate of the GDP deflator is 5.41 percent at an annual rate and there are 2 strong growth quarters, 2021:1 and 2021:2.

The prediction needs the values of the two-party vote share in the 2020 election for the president, Vp-2, and for the House, Vc-2. The value of the former is 52.27 percent (Biden), and the value of the latter is 51.57 (House Democrats).

The following gives a breakdown of the prediction using the notation in Table 1 and the coefficient estimates in equation 3a in Table 2 of the update.

48.89    Constant term
-3.14    Coefficient estimate of I, the party dummy. This is the estimated 
         (negative) effect for the incumbent party in the White House.
 1.14     0.725*(Vc-2 - 50) =  0.725*(51.57 - 50).  House incumbency effect.
-0.49    -0.214*(Vp-2 - 50) = -0.214*(52.27 - 50).  Estimated effect from the
          size of the presidential vote share in the last election (balance effect). 

46.40   TOTAL so far

-2.69    -0.449*Pcc.  Assuming Pcc = 6.0.  Negative inflation effect.
 5.28     0.493*Zcc.  Assuming 5 strong growth quarters, so Zcc = (15/7)*5 = 10.71429.

48.99   PREDICTED VOTE SHARE FOR DEMOCRATS

The predicted two-party vote share for the House Democrats is 48.99 percent. This is predicted vote share, not seats. Given the current way House districts are configured, a 49 percent vote share for the Democrats would likely result in fewer than 49 percent of the House seats.

The prediction shows that the Democrats gain more from output growth than they lose from inflation. They are also helped by the House incumbency effect. They are hurt slightly by the balance effect. The main negative effect is the estimated 3.14 loss for the party in the White House in the mid term election. The estimated constant term is also slightly in the Republican's favor.

This prediction will change in the next four quarters as more is known about the economy. It seems unlikely, however, that the economy will be that much different from what is assumed above in order for the prediction to change much. You can compute your own vote prediction using your own assumptions about the economy by clicking the above link.