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Solid Brown Lead in Final MA-Sen Models


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Republican Scott Brown holds a lead in all 18 alternative models of the Massachusetts Senate race polls, now including all polls released through 6:00 p.m. Monday. Our standard trend estimate puts the race at a 6.2 point Brown lead over Democrat Martha Coakley. The less sensitive alternative linear model puts the Brown lead at 7.3 points. Across all models, Brown leads by between 1.0 and 8.9 points. Three quarters of the estimates have Brown ahead by 4 points or more. 

Brown built this lead over the past week of polling with only some tentative sign of the trend flattening over the weekend. Of course the last available polls were completed Sunday evening so we do not know if any movement has occurred on Monday.

Here is a brief review of the polls and the various models estimated. First, the polls without any trend estimates:
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One of the unusual features of the MA polls is the large number of leaks from Coakley's internal polling. No one leaks without a reason, and her leaks have been consistently better for her than other polling taken at the same times (with one exception). Past analysis has found that internal polls are typically about 5 points better on the margin for the leaker than are independent polls, but that the internal polls do track the trend rather well. This raises a question of how to treat Coakley's polls. Below, I estimate the models both with and without the leaks included, so we can see their potential impact. I have not discounted them for the historical five point bias with internal polls.

First, let's estimate the local regression models that are our standard here at Pollster. These are not identical to the dynamic charts because here I am estimating the Dem minus Rep margin while our charts estimate each candidate separately. I estimate the standard model, a more sensitive and a less sensitive version, and then repeat with the leaked polls included.
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With the limited number of polls, the local its are not as smooth as in our usual trends with dozens or hundreds of polls. They may also be more sensitive to outliers. That is one reason to check the effect of sensitivity.  For the three models without leaked polls, the sensitivity matters a bit for the trajectory but hardly at all for the endpoints.  When internal polls are included, the trends end up a couple of points more Democratic, though still put Brown ahead in the end. (The more sensitive estimate touches dead even but that is due to a day with only an internal poll. The sensitive estimator chases that but then moves back down.)

Next I switch to even less sensitive linear models. The local trends show some non-linear movement, and suggest a small upturn in the last day of polling, which the linear models will miss. But with relatively few polls, much of the "bendiness" of the local trends is due to noise and overfitting the data rather than meaningful shifts. The linear fits are a hedge against the noise, at the expense of an ability to spot a reversal of trend. 
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With these models we can disaggregate the data by partisan affiliation of pollsters. This gives a range of estimates from most favorable to Republicans to neutral (no picking of polls) to most favorable to the Democrats. Here I include the leaked polls in the most Democratic model, using only Dem polls plus the leaked internals, and in one model with everything we have regardless of source. The result is a range of estimates. The most Democratic model shows a 1 point Brown lead. Others range from about 5 to about 9 point Republican margins.

A final variation in the models is to fit quadratic models to allow the trends to bend according to how much the data demand a bend. If there were substantial upturns (or downturns) at the end, the quadratic model could pick that up while still maintaining less sensitivity than the local regressions we started with.
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As it happens, the data don't demand much bend at all. The fit is only slightly better with the bend and the end points of the lines are only modestly changed.

Finally, let's see the garbage can of all the models at once, to see if any stand out as very different.
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There is a range of estimates, but all are below zero, indicating a Republican lead. The two most Democratic models (using only Dem polls plus the internal leaks) stand out as most different from the rest. Half of the models fall between -4.3 and -7.4. The two most Republican estimates put Brown's lead at about 8.8 points.

The caveats are that turnout may yet matter, for either side. Reps enjoy an enthusiasm advantage, according to the polls, but Dems might yet mobilize their voters beyond what the polling suggests. And there is the unknown of the GOTV efforts on Tuesday.  But if Coakley wins, this will be a major surprise, and the pollsters will have a lot to rethink about their methods. A win for Brown will have huge implications for the Democratic policy agenda and will put the fear of God into Democrats running in November. 

 

Comments
Alphatxs:

Is over, Brown will win. Still hoping for a miracle.

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Saj102:

No miracles here. The Democrats are getting beaten and badly. Obama tried for a hail mary with HCR, Cap and Trade, etc. and it was not caught but the game has 4 quarters and we are just a 1/4 into this. No reason for panic but a time for reason.

Obama will re-tune the message and approach. While I would prefer a slow go as I am tax lawyer and more conservative by nature, I see the merits of pushing forward with the program. Politico is out with an article tonight that says he will actually just go for it and adopt a more populist approach. As I understand it that possibly starts with putting health care reform up for a vote and letting the chips fall where they may. The articles also states that he will propose austere measured and financial reform that will piss off both the Dems and Reps. We will likely get a vote on Paygo this week which will be something to talk about at the SOTU. I see the President proposing (not waiting for a bill to be written) commissions like the one for base closures to deal with the deficit (one to determine deficit reduction, one to deal approve infrastruture spending, and one to reduce entitlement waste). These are no popular with either side but is necessary and I see him seeking consensus around these. Maybe he will also veto the recent spending bill. If so, what will the tea bagger / republicans or like minded Democrats crow about... I see these being accomplished this year.

BTW, I also expect a very simple health bill to be get passed by next month tackling insurance abuses and Medicare fraud. Let's see the Republicans vote it down.

Regardless, it will be an interesting year....

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Lou-NH:

Saj102

I am generally a centrist as I am guessing you are as well, however, I am not letting go of HCR. I am hopeful that the House will approve the Senate version and tweak out some of the budgetary issues through reconciliation. I am all for taking a strong fiscal position and cutting the deficit. I don't care for the commissions idea at all. Why have a majority if your not going to use it. The moderates will jump all over wholesale fiscal reform and I would love to see the repubs vote against that. Having said that, I would make sure that any belt tightening would be patently Dem owned legislation and leave the Repubs nothing to run on in 2010.

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LordMike:

They'll run on the economy. "Belt tightening" will strangle an already fragile economy that is only on life support as a result of massive government spending.

While I understand why the White House is doing this, it's a huge risk 'cos of the negative effects on the economy, and he'll still be branded as a big spender no matter how much he cuts or tries to cut.

The Senate bill will be passed and modifications made in an education reconciliation bill waiting for just that purpose, or will just be done in next year's budget. If they do a 10 year forecast, then that would work well for the program as a whole. I suspect that the jobs bill will also be put in the reconciliation bill 'cos the GOP will filibuster each and every bill no matter how consequential or benign. They will filibuster the naming of post offices if they can. So far, they've been rewarded handsomely or their obstruction and refusal to work with the administration. That also has to change. the GOP has not been made to pay a price for their obstructionism. They haven't been called out on it at all. As much as Obama hates it, he is going to have to abandon his "bipartisan" crap and get more partisan and fight.

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Tom:

By the way, Nate Silver at 538 now has Brown with a 75% chance of winning. In the '08 races, only six contests (MN Senate and FL, IN, MO, NC and ND pres.) had the leader with a less than 75% chance of winning with the underdog winning only once (IN pres, although MO pres was within recount range if they wanted one).

That said, I still wonder what the pollsters are projecting for turnout. The forecast for MA tomorrow is 1" to 2" of snow statewide, which could impact turnout.

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Lou-NH:

Tom:

You are dreaming if you think 1 to 2" of snow up here affects turn-out. lol

LordMike:
I tend to agree with you on all except deficit control. My point was that while the DEMS MAY lose the 60th vote in the dead zone we call the Senate, they still control a substantial majority. They should still put forth their agenda. It is said that reconciliation has to be used to get things out of the Senate but hey every President since Reagan has done exactly that. Bi-Partisanship is over-rated and never embraced by the minority. It is used to fan the flames of decent in the electorate.

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