As has been the case for three weeks now, once again there is no change in the Senate Snapshot. The most likely outcome remains 52 Democratic seats (that counts Senators Lieberman and Sanders). The chance of a Republican takeover, if the election were held today, is 1.5%. That is up slightly over the past three weeks, but not by much.

As I discussed on Monday, stability is truly the hallmark of the Senate Snapshot this year.

Senate competitive campaigns chart

Senate seat outcome odds chart

I’ve put a series of question marks next to the Alaska campaign, because I simply have no idea how to accurately poll a write-in campaign. It is an unknown.

Nate Silver published an article about election forecasting yesterday that really caught my eye. The following paragraphs suggested the possibility of an Ultimate Election Forecast for statewide campaigns that would eliminate the need for any other election forecasts (at least forecasts Presidential, Senatorial, and Gubenatorial campaigns). Here are the three relevant paragraphs from the article:

Senate candidates who have a lead of 6 to 9 points in the simple polling average, with 30 days to go until the election — about where Mr. Toomey’s lead stands now — are undefeated since 1998. This isn’t quite as impressive as it sounds, since there are only seven such candidates in the database. But if we expand the scope of our study just a bit, it proves to be the norm rather than the exception. Senate candidates with a slightly larger lead in the polling average — 9 to 12 points — are also undefeated. Candidates with a slightly smaller lead in the polling average — 3 to 6 points — have a pretty good track record, with nine wins against three defeats.

Indeed, no Senate candidate with a lead of more than 5.5 points in the polling average, with 30 days to go in the race, has lost since 1998: these candidates are 68-0. (Martha Coakley in Massachusetts would have been an exception, but special elections, where the polling can be much more erratic because of lower turnout, are outside the scope of our study.)

Candidates for governor with a lead of 6 to 9 points in the polling average, meanwhile, have a 9-to-2 record. If we combine their numbers with those of the Senate candidates, we find that candidates with a lead comparable to Mr. Toomey’s (6 to 9 points, with 30 days to go) have 16 wins against two defeats, which corresponds to an 89 percent winning percentage.

This caught my eye because it is very similar to the methodology I use for the Senate Snapshot. In the Snapshot, I take the simple 25-day polling average (leaving out Zogby Interactive and Columbus Dispatch polls), because I found that number of days to have the least error of any simple average in projecting the final vote margin from the final polling average. Then, I calculate the “current win %” based upon the percentage of instances the 25-day simple polling average has been incorrect by more than the current margin. (Actually, I take half of the percentage of times the 25-day average has been incorrect by more than the current projected margin, since I assume there is an equal chance for error to break in favor of the Democratic or Republican candidate.)

The Ultimate Election Forecast becomes possible by combining what Nate is discussing with what I am doing.  If you had an enormous amount of time on your hands, you could calculate the error between the simple polling average and the final vote margin at any point in the campaign for all Senatorial and Gubernatorial campaigns since 1998 (or earlier, if you have the data). For example, you could determine that simple polling averages taken 100 days before an election erred by 5.0% or more on the final margin in 30% of Senate and Governor elections. You could do this for any number of days before an election--50, 150, 7, 213, however many you wanted. All of them, really. If you did do that, then with you would be able to project the odds of victory or defeat in any statewide campaign at any point in the campaign. And you could do so with real certainty.

Now, I don’t have that much time on my hands. It took me a few weeks just to determine the odds of victory the day before an election. Determining the odds of victory for each of the 500 days before an election would be an utterly galactic undertaking. But, if anyone were to do it, then s/he would actually have ”The World’s Greatest Election Forecast, In the World,” and there wouldn’t be much need for any others.

If you want to be the ultimate election guru for 2012, and beyond, that is how you would do it. Any takers?

--Polling is not a conspiracy designed to manipulate your emotions.

--Polling averages don’t suck. They are quite accurate.

Actual Notes
--This is a snapshot, not a forecast. All of the odds presented here are based on if the election were held today. It is not a prediction of future trends.

--Only campaigns within 14% are listed. If a campaign isn't listed here, then it is not currently as close as any of the campaigns listed here.

--Lisa Murkowski’s odds of victory are included in the overall GOP total. Charlie Crist’s odds are split evenly between Democrats and Republicans.

--With few exceptions, all polls used in the averages are taken from Pollster.com.

--A complete description of the methodology behind this snapshot, along with all the research and a FAQ, can be found here.

Originally posted to Daily Kos on Fri Oct 01, 2010 at 04:46 PM PDT.

Your Email has been sent.