The Volokh Conspiracy

Are the Democrats Likely to Take One Chamber or Two?--

I’ve been looking at which party is going to control the Senate after the election, and I’m a bit surprised at some of the juxtapositions.

The Friday prices on the Iowa Electronic Markets show a 83.5% chance of Democrats gaining control of the House and a 33% chance of gaining control of the Senate (i.e., the Republicans having fewer than 50 Senate seats).

The Saturday evening TradeSports line is similar: the Democrats have an 87-88% chance of taking the House and a 31.6-31.9% chance of taking the Senate.

The House races are too numerous for me to make much sense of, but as I read RealClearPolitics, the Democrats need to pick up 6 seats to control the Senate, assuming that the probable 2 independents (Lieberman and Jeffords['s independent replacement Bernie Sanders]) caucus with them.

Likely pickups are PA (Casey +11.2%) and OH (Brown +11.2%).

Leaning Democratic is RI (Whitehouse +9.2%).

The other three possible pickups are listed as tossups (MO, MT, and VA), but the Democrat is ahead in the RCP poll averages in each race by 0.6% to 1.7%.

The Saturday night TradeSports bid/ask spreads also support Democratic victories in each individual race:

MO: DEM: 50.3% - 55%; REPUB: 46.1-48%.

MT: DEM: 65% - 68%; REPUB: 35-39.8%.

VA: DEM: 55.2% - 58%; REPUB: 43.3-48.2%.

So if each individual race breaks as currently polled, the Democrats win the Senate.

There is an outside chance that the Democrats could pick up one of the other two Republican seats that RCP lists as leaning Republican (AZ, 8%, and TN, 6.5%), even if it lost one of the seats listed above.

If each race individually goes according to the current polls and current betting line, the Democrats win both houses of Congress. But since so many races have to go toward the Democrats for them to win control of the Senate, both TradeSports and the Iowa Electronic Markets reflect about a 2 to 1 odds of the Republicans keeping the Senate.

I find this an interesting example illustrating joint probabilities: combining even highly correlated multiple probabilities more than 50% yields a joint probability significantly less than 50%.

Andrew Hyman (mail) (www):
Jeffords is retiring.

[Thanks. Correction made. --JIM]
11.5.2006 12:03am
DPT:
I too find multiplication interesting.
11.5.2006 12:14am
James Lindgren (mail):
DPT,

Ah, but you can't just multiply the probabilities without knowing how intercorrelated they are. If the probabilities were independent, you could.

Also, I think (but I'm not sure) that in the 2004 election every single state broke for the presidential candidate in accordance with the betting line on the night before.
11.5.2006 12:21am
Ship Erect (mail) (www):
What does this have to do with actual probabilities? This isn't fair dice or a deck of cards we're talking about, or even statistical analyses of past elections: everybody's just guessing.

What are the odds that these odds will seem pointless Tuesday night?
11.5.2006 12:23am
Truth Seeker:
What are the odds that these odds will seem pointless Tuesday night?

Tuesday night? If some races are close, there could be litigation for weeks, months, years? The lawyers probably have their complaints already drafted.
11.5.2006 1:09am
DPT:
James,

You're right. Although, I think it's a little hard to argue that the probabilities will be intercorrelated (much). I'm sure they are in some way: something to do with time-zone differences, etc.

Ship Erect,
You're right too but with the margin of error, and information on how the probabilities are correlated, then it does become a matter of probability.

It's been so long since I've taken statistics.
11.5.2006 1:09am
Chumund:
I think part of the explanation is the belief that the GOP may have some sort of systematic advantage (e.g., GOTV) that does not show up in polls.
11.5.2006 1:26am
CLS (www):
I had made detailed projections on the House, after hours of work and posted it on my blog at Blogspot . Yet after being on line for half a day it simply vanished along with all the work I did. I have reposted but not with the details I had before. In a nutshell here are my projections.

Senate: If Webb wins Virginia the Dems take the Senate BUT then I anticipate that Lieberman may suddenly have a change of heart and caucus with the Republicans not the Democrats. He knows who is funding his campaign and it wouldn’t surprise me that he is hiding his intentions from the voters. If he switches to the Republicans I also expect he’ll try another bid for the presidency as a Republican.

House: To me it looked like the Democrats have a strong chance of picking up 19 seats without much difficulty. In addition there are a couple of dozen other seats they can pick up. So I’m guessing a pickup of between 20 and 25 seats with up to 30 possible but not so likely.

Governors: Currently the split is 28 Republicans to 22 Democrats. I suspect those numbers will have reversed. In some ways these are more important to the long term trends in Congress as we will be redistricting soon and governors have a lot of influence on the process. The Republican Gerrymandered for their benefits (as have the Democrats in the past) and there is an increased likelihood the Democrats will do more in the future.

Not only has Bush been a short term disaster for the Republicans (and the country) but his ineptness will have long term implications for the party as well. While it is too early to say for sure it looks likely that redistricting will benefit the Democrats because of the Bush impact on elections for this election and I suspect for 2008 as well. He will increase the number of state legislatures and gubernatorial seats in Democratic control. And when redistricting is finished that will mean an increase in Democratic victories in the House for another ten years.

By embracing Bush and throwing out the Goldwater/Reagan legacy the Republicans have severely harmed themselves for the next 15 years I suspect.
11.5.2006 5:59am
Anonymous Jim (mail):
Wouldn't it be funny if the Senate ends up 50-50 and Chafee wins?
11.5.2006 7:11am
Arbusto Spectrum:
I would love to see odds being given on the likelihood that Lieberman, if he wins, switches party allegiance. In the northeast, that would be one very active contract...
11.5.2006 7:38am
Hari (mail):
A key variable is the number of seats that the minority party needs to win. Imagine two extremes. If the Senate were currently 50-50, with 34 incumbents running, 33 certain to win, and one seat having a 60% chance of switching, then the chances of the senate switching would be 60%. On the other hand, if one party held all 100 seats, 34 seats were up for grabs, and the oposing party had a 100% chance of winning each of those 34 seats, the odds of winning control of the Senate would be 0.
11.5.2006 8:21am
Duffy Pratt (mail):
I thought Diebold had eliminated probability from this election.
11.5.2006 8:23am
Bored Lawyer:
A couple of posters have raised a side-point which I was wondering about: Lieberman.

Since his own party rejected him from the nomination and he is running as an independent (with mostly Republican support), would he not be justified in switching parties? Or at least caucusing with the Republicans?

Does anyone know whether he has made any statements or promises on the issue during the campaign?
11.5.2006 8:48am
Oren Elrad (mail):

Wouldn't it be funny if the Senate ends up 50-50 and Chafee wins?


I would be amused mainly by the fact that Dick Cheney would have to leave his undisclosed location. He might even have to see natural sunlight!


Does anyone know whether [Joe] has made any statements or promises on the issue during the campaign?


He has, although I can't find a direct quote on the record. For instance, see


Despite his independent bid, Lieberman has said he will caucus with the Democrats if he wins re-election Tuesday.


Over here , the article states that Joe "pledged" to caucus with the dems.
11.5.2006 9:24am
Oren Elrad (mail):
There were supposed to be links in that past message.

Link One


Two
11.5.2006 9:26am
Ted Frank (www):
Lieberman has said he would caucus with the Democrats. Whether that's still true if the Democrats carry through with a rumored threat to strip him of his seniority on committee assignments is another question, but backwards induction suggests that the Democrats won't play that game of chicken. The Lamont candidacy does seem to have cost the Democrats a couple of vulnerable seats in Connecticut that they could have taken from Republicans there.

Jim, Maryland is also in play, with Cardin only a 3-1 favorite over Steele. Kean has an outside shot in NJ, too.
11.5.2006 9:45am
AppSocRes (mail):
All these probabilities are based on polls. It is easy to demonstrate -- by comparing poll predictions with actual outcomes -- that pre-election polling results have become steadily more bisased (in the purely statistical sense of the term) towards liberal candidates. I believe the reasons for this are manifold: conservative disgust and withdrawal from the whole process; response biases introduced by pollster attitudes (a recent study suggests that when a pretty little liberal grad student asks who you're going to vote for, you don't want to upset her); and absurd predictions of the composition of the voting population by liberal polling organizations. I don't believe that Karl Rove is whistling in the wind this time around. I think liberals are once again going to be shocked that Republicans retain control of both houses even though "everyone they know voted democratic."
11.5.2006 11:55am
Charlie (Colorado) (mail):
Ship, the point of using tradesprots is that while everyone is guessing, there is a well-known, if little understood, thing sometimes called the Delphi Effect: markets or polls of large groups of people tend to be surprisingly predictive. Or as John Brunner put it long ago "the surprising thing is that while nobody knows what's going on, everybody seems to know whats going on."
11.5.2006 12:52pm
Oren (mail):
AppSocRes, you can make a 500% profit on that prediction, why are you wasting your time posting a blog? Head on over to the Iow Markets and buy your RH_RS06 contracts for $.20 on the dollar!

Certainty is a lot different when you are actually ponying up the dough!
11.5.2006 2:11pm
lucia (mail) (www):
AppSocRes>> I think liberals are once again going to be shocked that Republicans retain control of both houses even though "everyone they know voted democratic."

You may be right, but I wouldn't wager any money on that!

I live in Dupage County Illinois, which is nicknamed "America's most Republican County" by the Chicago Tribune. I am addicted to eavesdropping and always have been. Four years ago, I never, ever, ever heard a single anti-GOP sentiment while eavesdropping in the county.

Times have changed!

Based on recent eavesdropping at block parties, health clubs, donut shops and grocery stores, I'd say the Republicans should be very, very worried.
11.5.2006 2:34pm
Speaking the Obvious:
"Based on recent eavesdropping at block parties, health clubs, donut shops and grocery stores, I'd say the Republicans should be very, very worried."

Donut shops, too? So even the police in Dupage County are voting Democratic?
11.5.2006 3:51pm
Aleks:
Re: then I anticipate that Lieberman may suddenly have a change of heart and caucus with

My prediction for Liebermann is that he stays in the Senate as a nominal Democrat for now, playing the role of bipartisan peace-keeper and deal-maker in a very closely divided chamber. But in 2008 he jumps shiop abnd accepts a VP slot on the GOP ticket with McCain at the top. Since McCain would almost certainly be a one-termer because of his age, that still gives Liebermann a shot at the presidency in six years.

Re; I think liberals are once again going to be shocked that Republicans retain control of both house

Given the level of public disgust with the GOP Congress, if the Republicans do keep the House I think it will be prima facie evidence of massive vote fraud and should thus be an occasion for the sort of public revolt that the Ukraine saw a couple of years ago in the aftermath of that rigged election. As for the Senate, yes the GOP will more likely than not keep control but only by a seat or two. DeWine and Santorum are goners, Chafee and Burns most probably so; Menendez is likely to pull it out in NJ (that's a very blue state remember, and if anything polls tend to over-predict for the GOP there), ditto for MD. There will be no surprises in MI, WA, MN or AZ (let alone FL or NV). TN is now looking Republican at this point, but I will go out on a limb and predict that either Allen or Talent get their pink slips (if it were my choice I'd keep Talent and can Allen).
11.5.2006 5:06pm
lucia (mail) (www):
peaking the Obvious:> Donut shops, too? So even the police in Dupage County are voting Democratic?


Can't say I actually overheard policemen at the Dukin' Donuts on Maple Ave... Come to think of it, I haven't seen policemen in that Dukin' Donuts. Maybe they prefer Krispy Kremes?
11.5.2006 7:02pm
Andy Freeman (mail):
> But in 2008 he jumps shiop abnd accepts a VP slot on the GOP ticket with McCain at the top.

Lieberman has a much better shot at the 08 GOP presidential nomination than McCain does. McCain's popularity is mostly outside his party, and it's his party that does the nominating. (Said outsiders will be working for Sen Clinton or to derail her run at the 08 Dem nomination, so they won't help him.)
11.5.2006 7:38pm
Bart (mail):
Now is the time to put your money on the GOP to hold the House at Tradesports.

Support for the Dems in the Washington Post, Pew and Gallup Congressional Generic polls have all collapsed dramatically over the weekend to levels consistent with the last polls before the GOP won in the last couple mid term elections in 1998 and 2002.

The GOP traditionally dominates absentee and early voting and both are higher than the 2004 during the presidential election. If the GOP candidate is anywhere close in a competitive district, go to bed because he or she will win the later count of absentee ballots.

This was an early indicator that the Dem talking point repeated endlessly in the press that the GOP was discouraged and would stay home is nonsense. The Pew poll today confirmed this GOP interest.

The GOP internal polls are beginning to leak into the blogosphere and they are claiming a loss of between 7-10 seats right now.

http://www.anklebitingpundits.com/content/index.php?p=1092
11.5.2006 9:13pm
Spartacus (www):
aleks: Given the level of public disgust with the GOP Congress, if the Republicans do keep the House I think it will be prima facie evidence of massive vote fraud and should thus be an occasion for the sort of public revolt that the Ukraine saw a couple of years ago in the aftermath of that rigged election.

Prima facie is a pretty strong word; but what about the substantive claim that in the recent past, polls have consistently been innacurate and biased in favor of the Dems (see 2002 and 2004). I didn't see a massive uprising after the supposed "vote fraud" in Ohio in 2004, and even the 2000 election didn't cause massive street protests. Maybe in the US life just isn't nearly as miserable as it is in the Ukraine (and candiates aren't being literally poisoned in assassination attempts) so massive civil disobedience is as unlikely as the actual voter fraud you suspect is possible.
11.6.2006 11:43am
Aleks:
Re: but what about the substantive claim that in the recent past, polls have consistently been innacurate and biased in favor of the Dems (see 2002 and 2004).

To be honest I don't recall the polls of 2002, one way or the other. However in 2004 the polls showed a very close race (essentially a toss-up) between Bush and Kerry, much as they had in 2000 between Bush and Gore, and in both years that was what we got: a very close race. And what bias in favor of Democrats? There were polls in the last days of 2004 that predicteed Bush would win NJ, MI, MN, OR, WI, and even HI. He did come close in a couple of them, but obviously did not win them, indicating a polling bias in the other direction.
11.6.2006 9:00pm