The Key House Races Pickup Prediction Model

KeyHouseRaces.com ^ | 14 October 2010 | Interceptpoint

[InterceptPoint]

Political Junkie Too, the resident statistical wiz at Freerepublic.com has taken the average KeyHouseRaces ratings by our 6 "Experts" for each of the districts on our Master List and built a computer model to generate an estimate of the outcome of the 2010 election for the House of Representatives. The model uses a technique known as a Monte Carlo simulation that utilizes probability functions for each of the KeyHouseRaces ratings categories - Leans D, Toss Up, etc and then runs a simulated election based on these probabilities.

As we started to get some decent poll data PJ Too decided to build a second model that utilized poll data less than 60 days old and, for districts where we had no poll data, to utilize the basic "Expert Rating" version of the simulation. The chart and the plot below show the calendarized results of this "hybrid" poll and expert-based simulation of the November election.

The results shown below are the average of 32,000 runs of the hybrid computer model each week since July 31st. Since the polls tend to lead the "Experts" it is not surprising that the poll-based simulation predicts a larger number of GOP seats than the Experts based model. This is simply due to the fact that Republican prospects have been improving weekly and the expert ratings updates tend to lag the polling data.

You can see the original Political Junkie Too Expert Base simulation results HERE.

Poll Based Model

The following chart summarizes the results of a 32,000 run Monte Carlo simulations of the outcome of the 2010 election for the House of Representatives based on polls that are available for the Key House Races Master List.  Where polls are not available, the "Expert" ratings are used in the same manner as is done in the  "Expert Ratings Model" simulation. The expected number of GOP seats shown is the rounded expected (mean) value of the GOP seats for the 32,000 runs.

Hybrid Expert - Poll Based Model
Week	House Seat Projection		Probability of GOP Control	Projected GOP Pickup
	GOP	Dem
31-Jul-10	212	223	8.43%	32
7-Aug-10	211	224	4.51%	31
14-Aug-10	211	224	4.44%	31
21-Aug-10	213	222	11.83%	33
28-Aug-10	217	218	42.58%	37
4-Sep-10	218	217	50.40%	38
11-Sep-10	219	216	66.39%	40
18-Sep-10	219	216	62.30%	39
25-Sep-10	218	217	61.17%	39
2-Oct-10	221	214	83.86%	41
9-Oct-10	223	212	96.15%	44

 

 

 

Poll Based Model

The data from the above table is plotted below.

The Dashed Red Line shows the probability that the GOP will re-take the House and it crossed over the 50% point on September 11th.

The Dark Black Line shows the trendline for House GOP seats that has steadily risen since early August.

That Purple Line at the top of the plot represents an estimate of the maximum number of seats that the GOP could pickup. Only 10% of the Monte Runs exceeded these value.

Likewise, the Green Line provides an estimate of the lower limit of the GOP seats - only 10% of the Monte Carlo runs fell below these values.

The bottom line: The trend is up and we need to keep it going up right to November 2nd.

[1010RD]

GOTV is critical. A big turn-out nationwide is needed and Obama becomes a lame duck. It’s why I’ll vote for Kirk.

That said, the real battles start after the election. You’ve got a savvy WH, vicious and willing to manipulate, plus a willing media and a House that can be like herding cats.

The GOP leadership has its work cut out. As the conservative vanguard we’ll need to accept the limitations of our system of republican government. There’s only so much they can do, but that still is a lot.

We need to win this November and for a dozen more to come to undo the damage to our nation.

[ken5050]

I see your point. However, I think that it will still hold true this year. Here’s why.. The House, which because of Pelosi, is the face of the Dem party and its agenda, is despised by the voters..so they want to vote out their Dem representative..and because it’s an off year...ticket splitting won’t occur..that’s why the Senate follow the House.