In the Senate: In critical states there are so many polls that fairly exact statements can be made. The probability of the Senate remaining Democratic is nearly 100%*. Assuming polls are unbiased on average, with 85% probability the following exact outcome is predicted: 51D-49R. Knife-edge races:
WA: Murray (D) over Rossi (R) by 2.0 +/- 1.0% (mean +/- SEM).
NV: Angle (R) over Reid (D) by 2.0 +/- 0.5%.
CO: Buck (R) over Bennett (D) by 1.0 +/- 0.7% (this is the real nailbiter).
IL: Kirk (R) over Giannoulias (D) by 2.0 +/- 0.8%.
WV: Manchin (D) over Raese (R) by 4.5 +/- 1.1% (statistically a little suspenseful because only n=6 for recent stable polls).
All nominal win probabilities are over 90%.
In the House: The Republicans will take control. By the same methods as before, we’re at 230R-205D. The 95% confidence interval for a gain of 50-54 seats to 228-232R. Pollster currently has 27 “toss-up” races with a total of over 100 polls, an amazing number.
P.S. For the record, as of 10PM tonight, two model-intensive comparables are FiveThirtyEight Senate 51.7D, House 233.1R, and StochasticDemocracy Senate 52.2D, House 237.7R. Both House results are outside my 95% confidence interval. I am interested in how far my simple-minded approach can go toward top-line characterization. But who knows, maybe there’s unseen complexity.
*This goes down to 90% if there is a 50-50 split and Lieberman jumps ship again. 100% if he stays with the Democrats this time.