The final Senate forecast

Now it's time to do the final senate forecast.

Close races

All in all there are 45 safe seats for the republicans and 46 for the democrats.

State	Margin	SD	% Dem win	% GOP win	Dem senators if dem win	GOP senators if GOP win
Colorado	Bennet (D) 7.4%	-1.85	96.78%	3.22%	46	55
Wisconsin	Feingold (D) 2.7%	-0.68	75.17%	24.83%	47	54
Pennsylvania	McGinty (D) 2.0%	-0.5	69.15%	30.85%	48	53
Nevada	Masto (D) 1.8%	-0.45	67.36%	32.64%	49	52
Indiana	Young (R) 0.7%	0.18	42.86%	57.14%	50	51
Missouri	Blunt (R) 1.3%	0.33	37.45%	62.55%	51	50
New Hampshire	Ayotte (R) 1.5%	0.38	35.20%	64.80%	52	49
North Carolina	Burr (R) 2.0%	0.50	30.86%	69.14%	53	48
Florida	Rubio (R) 3.2%	0.8	21.19%	78.81%	54	47

Whereas the presidency favors Clinton, the Senate favors the GOP. As it stands, there is about a 57.14% chance that they will control the senate, and a 37.45% chance that the democrats will. This means that there is about a 5.41% chance of there being a tie. The single most likely outcome has the GOP winning 51-49. Of course, this method is very simplistic. In practice, if each trial were independent of the others, the chance would go up for the GOP dramatically.

The original version did try a methodology that treated the four races most likely to influence the outcome as separate from one another, but all in all, I figured that due to shifts in data and due to there only being one toss up, it was a good idea to toss out this particular model. The only true (<1%) toss up is Indiana. As such, I'm going to just rely on my original model in determining the outcome, expecting the democrats to take 4 and the republicans to take 4. This means the likely outcome for the senate is either a tie or a republican win, but the democrats can prevail if they move into republican territory in Missouri or New Hampshire.

All in all, it should be noted that this is a very competitive race. There is a chance for each side to take the senate, and there is a pretty decent chance of a tie. Much like the presidency, while the odds favor one side over the other, the margins ensure that there remains a chance that anything can happen.