House Prediction for 2022: October 29, 2021
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, which discusses the equation, has been read.

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,


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.
 1.84     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.

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 prediction using your own assumptions about the economy by clicking:

Compute your own prediction for 2022.