Posted on 08/28/2014 9:15:35 PM PDT by Theoria
[Note: this is a work in progress. I'm basically seeking comment as I develop a November predictive model. Please give your feedback... -Sam]
I’ve been asked why the PEC Senate poll snapshot is more favorable to Democrats than forecasts you’ll find elsewhere: NYT’s The Upshot, Washington Post’s The Monkey Cage, ESPN’s FiveThirtyEight, and Daily Kos. All of these organizations show a higher probability of a Republican takeover than today’s PEC snapshot, which favors the Democrats with a 70% probability.
Today I will show that in most cases, added assumptions (i.e. special sauce) have led the media organizations to different win probabilities – which I currently believe are wrong. I’ll then outline the subtle but important implications for a November prediction.
If you want to get caught up on the major approaches to Senate models, start by reading my POLITICO piece. There I categorized models as “Fundamentals-based (Type 1)” and “Polls-based (Type 2)”. The major media organizations (NYT, WaPo, 538) have all gone with a hybrid Type 1/Type 2 approach, i.e. they all use prior conditions like incumbency, candidate experience, funding, and the generic Congressional ballot to influence their win probabilities — and opinion polls. What does that look like?
The first data column is the current PEC poll median. The next two columns show what a polls-only win probability looks like. Finally, the last three columns show the media organizations’ win probabilities. All probabilities are shaded according to who is favored, the Democrat (blue) or the Republican (red). “sum6″ is the sum of probabilities (converted to seats) for six key races: AK, AR, CO, IA, LA, and NC.
Let me make some general points.
Senate Democrats are doing surprisingly well. Across the board, Democratic candidates in the nine states above are doing better in the polls-only estimate than the mainstream media models would predict. This is particularly true for Alaska, Arkansas, and North Carolina. In these three states, Democrats are outperforming the expectations of the data pundits (The Upshot’s Leo, Nate Silver, Harry Enten, John Sides, etc.). Why is that, and will it last?
“Fundamentals” pull probabilities away from the present. For PEC and Daily Kos, the win probability is closely linked to the poll margin. The Daily Kos model was created by Drew Linzer, of Votamatic fame. Both are based on polls alone.
The mainstream media organizations are a different story. They show a general tendency to be more favorable to Republicans. For Alaska (AK), Arkansas (AR), and North Carolina (NC), the discrepancy between PEC/DKos and NYT/WaPo/538 is rather large. Where PEC shows an average of 4.02 out of 6 key seats going Democratic, those organizations show 2.75 to 3.16 seats. This key difference, 0.86 to 1.27 seats, is enough to account for the fact that PEC’s Democratic-control probability is 70%, while theirs is between 32% and 42%.
Longtime readers of PEC will not be surprised to know that I think the media organizations are making a mistake. It is nearly Labor Day. By now, we have tons of polling data. Even the stalest poll is a more direct measurement of opinion than an indirect fundamentals-based measure. I demonstrated this point in 2012, when I used polls only to forecast the Presidency and all close Senate races. That year I made no errors in Senate seats, including Montana (Jon Tester) and North Dakota (Heidi Heitkamp), which FiveThirtyEight got wrong.
In 2014, these forecasting differences matter quite a lot. This year’s Senate race is harder than any electoral forecast that the other forecasters have ever had to make. To be frank, 2008 and 2012 were easy. My own experience is guided by 2004 Presidential race, which was as close as this year’s Senate campaign. In 2004, I formed the view that the correct approach is to use polls only, if at all possible.
The present is more sharply focused than the future. DailyKos, the Upshot, and FiveThirtyEight have win probabilities are closer to 50% than PEC’s in 18 out of 27 cases. This mostly reflects the fact that they are trying to predict November races on an individual basis. Generally, this drags their total expectations toward randomness. This reason also contributes to why their expected number of wins in key races is closer to 3.0 than PEC’s 4.02.
The exception is The Monkey Cage, which shows higher certainty than PEC in 6 out of 9 races – but sometimes in the opposite direction. This suggests that their model must be heavily weighted toward fundamentals. That is very brave of them.
Can a prediction be made from polls alone? This is the question I am currently wrestling with. Using the 2004-2012 campaigns as a guide, I suggest that the Senate campaign’s future ups and downs can be gleaned from looking at what’s already happened since June 2014:
The PEC polling snapshot has mostly favored Democrats. Starting from June 1st, Democrats have led for 61 days and Republicans for 26 days, a 70-30 split. During that period, the Senate Meta-Margin has been D+0.24±0.57%. Assuming that the June-August pattern applies to the future, I can use this Meta-Margin, and the t-distribution with 3 d.f., to predict the future, including the possibility of black-swan events. The result is that the November Senate win probability for the Democrats (i.e. probability that they will control 50 or more seats) is 65%.
Finally…I note that this is all a work in progress. I’m using PEC as a sandbox for kicking around ideas. With that, I invite reader reactions.
2014 election will be crazy close.
It’ll be a GOP blowout. You heard it here first.
I hope you are correct.
I think what Obama does in the next two weeks will decide it. Or, more importantly how we (as in We the people) react to it.
How do you exceed expectations as a Dem? "Now with 34% more fascism!"?
I can believe this for one reason.
The GOP has not laid out a platform, vision or details on what they will
do if they take the senate and maintain the house.
I have heard nothing other than Reid and Obama are bad.
The GOP would be wise to tell the American people what they would
do with the power other than just run against Obama and Reid.
Has anybody heard what the GOP is running on?
That’s precisely my take, and while I think they will squeak it, it won’t be a barnburner.
Hot air, mostly.
“Has anybody heard what the GOP is running on?”
Empty.
I wish you were right, but how many illegal aliens brought in by team Obama will be voting Republican? These polls are manipulated to factor in voter fraud. Making the expectation match the vote count, including the voter fraud. That way there’s no surprises.
So sets The Princeton Election Consortium.
I thought the same thing during the last presidential election. Bought coal stocks convinced that Obama was toast, and lost my shirt.
I wouldn’t bet on Milt doing anything other than capitulating, this is different. The fact that Officer Darren Wilson has raised more money than Michael Brown’s family, despite all the negative press and positive for Brown tells me something’s afoot.
This is one of the most frightening times in our history. So much of the left, and independents are so taken by the dark side it is scary uncertain which way it will go.
One example that Rush brought up today is important to seeing how easily the masses have be swayed to the dark side. Statistics and polling shows that more voters now/still see Bush as the reason for our terrible economy.
Rush was trying to make a different point, but it can also be read as showing that so many, maybe even more voters have been swayed to the dark side than even 3 years ago.
This election will be harder on the right than many see. When you add in the voter fraud that will be prevalent (no DOJ to even think of confronting it), I think we could sink deeper into the slime than we are today.
Only prayers and with God's help will we avoid a terrible route this cycle.
See my tag-line it is truer than ever.
History tells us that a president’s party almost always loses big in his sixth year. Combine that with the “silent majority” backlash to all the scandals, wars, riots, disruptions, economic travesties, Obamacare, rampant inflation & unemployment and all the rest. If the Democrats somehow retain control of the upper chamber you’ll know that fix was in from the get go.
I hear what you are saying. And, normally, I would agree.
But, this time around, I'm not so sure.
Because I don't detect any corresponding enthusiasm for Republicans and their ideas (of which there seem to be none that they're willing to talk about). In 2010 (and 2012), the "broken glass Republican" was a common creature. This time, so far, not so much.
In 2010, the Republicans at least seemed committed to cutting spending and killing Obamacare. And they rode on the wave created by these two issues. But, after four years of inaction, four years of playing the accomplice, nobody truly believes the GOP is going to do anything about these concerns.
Indeed, we worry that the party may now be committed TO big government and Obamacare.
In its current state the GOP doesn't elicit a helluva lot of confidence or enthusiasm, much less excitement. It would not shock me if the Democrats were more successful with their GOTV efforts than the Republicans are with their's.
The GOP will hold the House and gain +4 in the Senate.
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